A one-year extension means "prove it, and prove it now, buddy." Jim Caldwell got a one-year extension last year, with the expectation that he had to get the Lions in the playoffs AND win a game, or at least be super competitive against what would have been perceived as a better team. An 8-8 record thus did not cut it.
So I think Mikey-Mike IS on the hot seat, and in my estimation he should be. His firing of the DC (with which I agree), but especially the cleaning out and re-arranging of his offensive staff, plus his whining for better talent, amounts to throwing everyone else under the bus. So now that Baby Mikey has gotten all he wanted, he better not have another disappointing season. Do they need to get to the NFC Championship game? Depends. If the team's big guns stay relativelty healthy and the team health overall is decent, then yes. But if big names go down and some position group gets decimated, but Mike sneaks them into the playoffs with a 10-6 but gets beat right away, he might be able to keep his gig.