Okay, but from what I've seen Snaps are better (from the perspective of flexibility and simplicity) than Flatpak, isn't this a case where it'd be better for GNOME to adapt rather than vice versa?
In distros yes, but in market snappy has been well received
https://partners.ubuntu.com/programmes/iot . For me the next move of which package manager will be adopted is gonna be based on companies which are gonna develop on it and get support. Only when Red Hat enters the game, you'll see a big adoption of snaps. For now, Canonical is ahead in this game.
If they are going to integrate gnome with snaps and snaps having an actual market, I doubt flatpak can compete against them. BUT, it would be easier for Canonical if they do something with their CAL, that'd be the real game changer.
There is nothing to strip out. The GNOME Software app (an app store) has an optional Flatpak plugin but except for that, nothing in GNOME depends on Flatpak.