This would almost certainly be illegal (antitrust violation) and probably wouldn't be worth the firestorm even if it was legal.
OK they'll raise seller prices and offer discounts for exclusivity.
Exactly. Or just lower vendor search rankings.
Amazon banned sellers from selling anything that competed with their firestick (Chromecast, Apple TV, etc ) for the longest time.
Will probably do nothing at least for now .. Google had the reputation to cut things that didn't grow as fast as it wants to, I don't even know for sure if Google Cloud will still exist in 2030.