Kraft actually talked about that, saying they try and hire the best people they can find in every aspect of his businesses, which is what he already said he planned to do in this case.
At the end of the day, and to your point, Mayo will obviously take the lead and has already made it clear he's not afraid to "rub people the wrong way," which he said is "part of the job of being a leader."
“When people talk about rubbing people the wrong way, I mean, that’s part of the job of being a leader, is to rub people the wrong way,” Mayo said recently,
via Karen Guregian of MassLive.com. “And I always try to be constructive and respectful with my feedback. Some people appreciate that transparency. Some don’t. But at the end of the day, if we can’t rub people the wrong way, how do you expect that you can be the best that you can be? And I would say, anytime there’s change, or anything like that, it’s going to be painful if someone rubs you the wrong way. At the end of the day, you have to look through all the words that really get to the substance and the meat and potatoes of what that person is trying to say.”
And he clearly knows he'll be accountable. If they go multiple seasons with a losing record and they're a mess, he'll be let go and a change will be made. But Kraft is doing the best he can to surround him with good people at the top and it certainly appears like he'll have an opportunity to bring in his own people as well.
So, to your point, we'll find out if this was the right move. I understand being concerned with whether or not it is the right move, but we won't find out for at least another two seasons (probably at the very minimum, given where they are right now, barring some incredibly good luck) if that's the case. Just have to let it play out.