So just as some see a dire future, I see a future as bright as any.
I don't see that assessment in any way realistic. While our future may not be "dire", I think it's hard to argue this team's future is on the same level as Portland, Miami, Seattle, or any of the other teams with young superstars. Not all of those teams will achieve success, but at least some of them are likely to. The Celtics, on the other hand, are going to face a very difficult transition, rebuilding without high draft picks or cap space. The team's future success will have to hinge upon one of the following strategies: 1) hoping to find a diamond-in-the-rough late in the draft who develops into an all-star caliber player, 2) hoping we can cash in the expiring contracts of Ray and/or Pierce for a free agent superstar, or 3) hoping that Rondo becomes a transcendent player who can lift less-talented teammates into contention.
All of the above are possible. However, I think the likelihood of that happening is substantially less than, say, Oden becoming a top-tier center, or a combo of Wade/Marion/Rose (for instance) becoming a long-term Eastern Conference contender.
As for your other points concerning how a young team may have never been as good as this one, I absolutely agree. However, I think just about anybody (including Danny) would acknowledge that the team sacrificed some of its long-term future for the ability to "win now". That strategy is paying off in a big way, of course, but that doesn't mean that our future is just as rosy as any other team's.
Personally, at this point I couldn't care less about the future, and I accept future rebuilding almost as an inevitability. That doesn't bother me, though, because there's a very good chance that this team wins a championship, or even more than one, over the next 3 - 5 years. However, I do not envy the future of any team whose roster structure is: potential borderline all-star (Rondo), talented but ultimately mediocre players (Perk, BBD, Powe), large expiring contracts, late-round draft picks (minus the 2009 pick), and no foreseeable cap space. The expiring contracts are nice, but sometimes its easier said than done to cash those in (not even taking into account whether Danny will want to ship, say, Paul Pierce out of town at the end of his career.)