I said this in the other IT thread, but if the plan is to remain competitive and we are able to acquire another all-star level player, then re-signing IT is a no-brainer. We will be over the cap (or very close to it) with said all-star, Horford, and Smart/AB being re-signed and letting IT go would only allow us to sign a low salary player to replace him. That player is very unlikely to be as impactful as IT.
The question, "Is IT worth $25M/yr?" isn't specific enough. If we are trying to be competitive, then of course he is (we aren't paying the luxury tax, Wyc is); if we are just a middling team and are unable to acquire any all-star level talent, then it might be time to not only sell off IT, but most of our veteran talent.
It really depends on what Danny is able to do via trade and free agency. My guess is he will make a strong run at making the team as good as possible.