I know this is Titletown and all, but if we put that aside for a second, I think there's no question we win more games over this time period in our current incarnation than if we'd kept IT. Not to mention, regardless of how last season shook out, we did make the ECF and came within a few minutes of the Finals. It's easy to forget now but Kyrie gave this team such a swagger in the first half of last season that I feel helped those young guys mesh and grow. If Kyrie walks we still have a really great group of players that could entice a free agent or compete on their own. And if Kyrie walks I really think players and the league overall will be saying, "what's the deal with Kyrie?" NOT "what's the deal with Boston?" I.e., his leaving will not prevent future signings or success.
Still. Easy to say something wasn't "worth it" in hindsight, but really, you just need to build assets and put your team in a position to succeed. If it falls short, so be it, as long as you've given yourself a shot. In Boston that means competing for a title. Wasn't ever going to happen with IT at the helm (sorry to say) so we had to take a shot.