With all due respect, this is my pet peeve in sports discussions re: coaches. When someone says the coach should be canned, and people say "Well there isn't anyone to replace him." Yes there are. There are hundreds and hundreds of brilliant football minds ready to be an NFL HC. Ditto for an NFL OC, because we don't really have an OC. (Perhaps "hundreds and hundreds" is an exaggeration, but you get my point) Unless you know the entire landscape of all NFL and FBS coaching staffs, you can't really say there isn't someone better to replace him.
If everyone prescribed to the cop out mentality of "there are not many better candidates," then guys like Jon Cooper, Jared Bednar, Spencer Carberry and Ryan Warsofsky would never end up an NHL HC.
Point there, there so many brilliant football minds would be make for a great Niners OC and great Niners HC. None of us can really say "there are not many better candidates."