Part of me worries the timing for the GM switch was unfortunate. I know a lot of people wanted TT gone for whatever reason. Let's put those aside and just think about timing alone.
Scenario 1: DC was fired as DC. If TT had one more year, M3 would hire a DC without issue or anything hanging over the hiring decision. The DC comes in, they both get a year together. At the end of next year, Murphy retires TT. The new GM comes in and can assess the staff as a whole and decide whether to keep them all or move them in a different direction.
Scenario 2: DC was not fired as DC. TT was retired this year. The new GM comes in and can asses M3 and DC and make a call on them together.
Instead we have Scenario 3: DC was fired and TT was retired. In almost makes the GM's job more difficult because he is not getting a fair chance to assess an embedded staff. There are going to be a lot of growing pains this year.
I like M3 as a coach, but I'm starting to come around to the idea that if the DC (basically the second head coach when the HC is an offensive specialist) and the GM were fired/retired the same year, they might as well clean house completely. There is going to be a lot of moving parts, and the hiring of the DC/GM are going to affect each other. I think the complexity adds risk in that the decisions are less likely to pan out versus if they happened in successive years.
I may be way off, but this almost seems like the riskiest timing for prolonged organizational success versus either successive year changes or cleaning house completely. (For the record, I think cleaning house completely holds its own significant risk as well.)