I think it's a bit early to compare Josh Allen and Patrick Mahomes considering Mahomes is a year further along and is surrounded by tons of talent.
Saying that, the situation the Bills are in with Allen is entirely McBeans fault. If the plan was to start Allen from the get go why did they wait until the 5th round to draft an OL and the 6th round to draft a WR? Instead they drafted a LB(giving away picks for that), a DT, a CB and a Safety before addressing anything on the offensive side of the ball. This was of course after they knew Wood/Incognito were gone and the most they'd done in FA was picking up Bodine and a WR Kerley, who they've already cut.
So maybe their plan was to sit Allen? Well that has failed miserably as well. They made no attempt to be aggressive in finding a place holder QB and were content signing the last QB off the scrap heap. Who they then traded and rolled into the season with freaking Nathan Peterman.
Yes, they have loads of money for FA next year and they have the draft. They also have a huge lack of talent across the entire team. The Bills need at least 3 OL, at least 2 WRs, a TE, probably a RB. They also will need to replace some players on defense, another LB, DT, DE and probably a CB. And those are all starters the Bills need, the Bills then need depth as well. They will need to absolutely knock it out of the park in the draft and FA, and then some.
I don't think anyone should be fired, that's ridiculously reactionary but it certainly does raise an eyebrow as to what exactly they are doing but 'Trust the Process',