I agree with almost everything you said but the last part. Well, maybe I agree with it, but just don't see it happening. Since Snyder has owned the team here's what he's done with the GM/VP of football operations role:
Charley Casserly - 1989-1999 - General Manager - Respected football mind who was let go shortly after Snyder got the team. This is typical for new owners to have their own guys in important roles.
Vinny Cerrato - 2000-2009 Director of Player Personnel, Executive VP of Player Personnel/Football Operations - Vinny was terrible for almost all of 9 years. His best offseasons where when he pathetically reached for players far past their prime.
Marty Schottenheimer - 2001 - 2001 - Head Coach/de facto General Manager - Just a space filler when Vinny was fired.
Joe Mendes - 2002 - 2002 - VP of Football Operations - Who? Almost forgot him. He's been a scout and is now a player agent. Very forgettable with it comes to what this team built.
Bruce Allen - 2010 - current - Executive VP/General Manager, President/General Manager, President - He's more qualified than Vinny or Mendes and has taken a lot of pressure off of Snyder. In my personal opinion he does a great job at taking a brunt of the PR backlash for what what the Redskins do, which in Dan Snyder's eyes has to be an asset.
Scot McCloughan - 2015 - 2016 - General Manager - Many respected him as a football mind and scout. He was publicly shamed for being a drunk and it appears his lawsuit for defamation has been dropped/settled.
I mentioned this in another thread, but what faith do you have in Snyder picking a better person for the job? I'm not saying Allen is good or even average, but he stuck with Vinny for 9 years. I know many have hope, but I truly feel if Dan was picking a new GM he'd probably grab a guy who under-qualified for the role and be very slow to move from that person.
Here's the thing with Allen - He hasn't built a champion, but he's been around them (Tampa) and has made things better in both Oakland, Tampa (after a step back) and I'd argue he's made Washington better in stints. I don't know if he's worse than whomever Snyder would hire. If people feel 'anything has to be better than Bruce Allen', then we have to move on. If we are objectively looking at his resume vs. the field then I still think after two injury filled seasons we don't know what he can offer.
I wouldn't disagree with either keeping him or moving on. I also think this team is so screwed at QB it might not matter who the GM is, so mind as well let Allen get all the blood on his hands for the 2019 season.