I've thought about this too. I'm not saying BS is coming to IU but I'm in the camp that believes there was an awful lot of smoke and things fell apart. But maybe they didn't. Even with all the conspiracy things out of the way, Boston is toast this year and everyone knows it. That's 8 seasons as HC without a title. It's NEVER happened in Celtics history.
I don't follow the NBA enough to know but is the trajectory of Boston in the next 2-3 years one in which they win titles? Are they better than Philly? Milwaukee? Brooklyn? Heck KenPom has Indiana & Atlanta as better than Boston as I write this. Then there is the West. Are they going to be better than Denver, LAC, LAL, Utah, Phoenix, Portland or even Dallas. Like I say the leash can't be "Hey, BS is our guy & we'll continue on for 20 years no matter what." His seat is warm (at least by media/fans standards) and it's only going to get hotter.
Brad is a smart guy. If he hasn't applied game theory to his own situation then I'd be shocked. Maybe he really does want to be an NBA executive. If so then all this is moot, but if he really does want to be in coaching, then the timing makes sense to jump unless he's 100% invested in being an NBA coach for the rest of his career. I guess it could later too, but right now the timing makes sense.
My ultimate nightmare though is BS passes up IU, we move on, and in 2-3 years, the Celtics haven't make a run, BS's seat is ON FIRE and he decides to go back to college when Duke or UNC open up. Yikes.