The good and bad thing about the 76ers' current state of supreme flexibility is that we don't have a ton of players that we know for a fact are gonna be a big part of this team's future. In the long-term sense, just about everybody on this team is expendable, and it wouldn't be hugely surprising if two years from now, at least ten of the 12 guys who played the most minutes for the Sixers this year were wearing a different uniform (or in some cases, possibly out of the league altogether). Evan Turner, Spencer Hawes, Jason Richardson, Arnett Moultrie, even Kwame Brown--all of them can be had for the right price.
The only true untouchable on the team is probably Jrue Holiday, the team's 22-year-old point guard. He made his first All-Star team this year, the youngest player in franchise history to do so, he kept the team in playoff contention for about half the season (before running out of gas after the All-Star break), and he's signed to a bargain of a four-year / $41 million contract. Unless they're dealing for an MVP candidate--and there aren't a ton of those out there for the dealing--any deals they make are going to be to find a complementary player for the Damaja.
The real question is about Thaddeus Young, the Sixers' second-most-valuable player. Like Jrue, Thad had something of a career year last year, averaging career highs in rebounds, assists, steals and win shares, while playing the most minutes of his career, proving that he can be a starting forward for a good team in this league, maybe as a sort of poor man's Shawn Marion. And like Jrue, Thad is signed to a contract that now seems extremely reasonable, under team control for another three years and another $27 million or so.
However, Thad probably ranks below Jrue in terms of trade value for the Sixers and around the league, mostly as a function of his being a couple years further along his carer than the Damaja, and there being more of a sense that this is probably about as good as Young is gonna get as a player. He could expand his shooting range a little (though he'll probably never be a real three-point threat) and he could further improve his ball-handling (which he's already made great strides with), but he's probably a little too slight and undersized to be enough of a post presence to grow into a 20/10-type player. He'll always provide value in subtle ways, but he's not too likely to become a star, in the conventional sense.
So Thaddeus Young stands not only as the Sixers' second-best player (and probably top all-around producer), but also as their most valuable trade chip, a player any team would love to have, on a contract that many teams could easily absorb without it becoming problematic. If the Sixers wanted to add a second core player to build around, along with Jrue, including Thad in a deal for that player would likely be the most efficient way to do it.
For instance--and I'm not suggesting that they should actually do this--the Sixers could probably make a real run at star Lakers big man Pau Gasol in the final year of his contract using a deal built around Thaddeus and an expiring contract or two. Thad would offer the Lakers a chance to get younger and more athletic, and his defensive versatility would help them further cover up the defensive deficiencies of their aging Nash-Kobe backcourt. He'd also help Mike D'Antoni by being able to play the three or four, allowing them to use him in small or big lineups, and his finishing ability would be a fantastic weapon for Nash and Kobe on the break or in the fast court.
However, you might look at all that and rightfully ask: If Thad is that good, and that valuable, why would you trade him at all? Why not keep him long-term and build around him and Jrue as the nucleus of the team's future? Having two young, cheap players like that locked up on team-friendy, multi-year deals is a pretty good starting point for any young team, and if you could add a third worthwhile core player through the draft or free agency without giving up Thad, wouldn't that be the better long-term play?
Undoubtedly it would, but unfortunately, that's much easier said than done. Barring a lottery miracle--their second in four years--the Sixers will likely have the 11th pick in this draft, said to be historically weak, and chances are much better of them adding a quality rotation piece than a true difference-maker. And if they keep both Jrue and Thad around for the next few years, that'll probably be good enough to keep them out of the top ten of the draft for the foreseeable future, meaning they'll have to strike late-lottery (or early-out-of-lottery) gold with another Jrue Holiday (who the Sixers nabbed with the #17 pick in 2009) to add another core player that way.
As for free agency, having Jrue and Thad is a good start to landing quality free agents. However, the Sixers don't have quite enough financial flexibility to add a max guy this off-season, and the free-agent class next season is pretty weak. And in the meantime, the rules of the most recent Collective Bargaining Agreement have so incentivised players to stay with their current teams (who can award them more years and more money per year than any new team) that the only reason marquee free agents have to really switch teams are to play in a major market or chase a championship, neither of which they would necessarily be doing if they signed with the Sixers.
This is all pretty broad-strokes stuff, but I do believe that generally speaking, it'd be much easier to add another difference-maker through trade than through other avenues, and Thad is their best asset with which to do it. And if so, I think that would ultimately be a sacrifice the Sixers have to make--as wonderful as Thad has been, he hasn't been good enough to be the second-best guy on a Sixers team that would actually contend for anything, and even though his production last year was his best yet, it was more due to an increase in minutes and role than any tremendous strides he made as a player, as his percentages and rates for the season--field goal percentage, PER, win shares per 48, etc.--were all basically in line with his last two years' averages.
That's not to diminish his accomplishments--being able to maintain that level of production in big minutes is a huge accomplishment in itself, and Thad proving he could do it was a huge step for his career. But as previously mentioned, it's hard to see him getting that much better from here, and a guy that gives you 15 and seven with solid peripherals and excellent defense is still more of a complimentary player, a third or fourth option, on a title-caliber team. Thad could easily put a team close to contention over the top, but it's hard to see him elevating a lottery team like the Sixers to that status without a whole lot of help. So if the right trade opportunity came along, I would like to see the Sixers open to trading Thaddeus, though not for anything less than an established star (or at least a player with the upside to be one), or a likely high future lottery pick.
Of course, as with so many of our Ten Biggset Questions, the Funny-Looking Kid With the Big Hair looms large over all. If the Sixers do end up rolling the dice a second time with Bynum, that high-upside guy they could get without giving up any other assets besides cap space, it might be worth holding to Thad for at least another year, since he would be an excellent frontcourt complement to Bynum, especially if he can be enough of a mid-range threat to give Drew some space on offense. But if Bynum is a no-go, our chances are better at getting the player we thought he was gonna be for us are better if we deem Thad expendable in such pursuits. Sad, but that's just how player acquisition works in the NBA.