A few things:
1) I think it's unlikely Ray or KG retires. They'd both be walking away from a ton of money. And if they do win #18, the temptation to win #19 will be strong (2 titles is impressive, 3 titles with a first ballot Hall of Fame career gets you put into some very exclusive conversations). If they fall short, I see them wanting to give it one last go, especially if next season is short.
2) I think we potentially have the surrounding talent to rest KG and Ray (and Paul) next year more. If Doc figures out his rotations better, West, Green, and Baby could all play closer to 25 mpg+ and really take the burden off of these guys without losing a ton on the floor.
3) I think the biggest question is whether we actually gain anything from "blowing it up." As I was saying to someone else the other day, who exactly is going to want an aging Kevin Garnett, Ray Allen, or Jermaine O'Neal? Bad teams will have no interest, since none of those player can make a bad team a contender. Borderline teams like the Knicks, Sixers, and Hawks could be interested, but what are they really going to give us? If they give up any of their young stars, the trade won't make it enough of an upgrade on their end to make it worthwhile and most of their draft picks will fall in a fairly unimpressive range.
Ultimately, I think the C's are likely going to be better served clearing cap space when these guys retire and then looking to bring people in.
So I think regardless of your confidence level about next year and regardless of what happens this season, this crew is coming back for one last hurrah next year.