I feel like there is literally no reason to play regular gambit anymore.
Regardless of whether you like them or not, Gambit Prime is objectively better than the original, and I feel that keeping the breakneck bounty and other bounties (clan, eververse, etc) locked to only Gambit is very restrictive. When you added the forges, it made some sense to have the world's bounties still count, but this is literally just a straight port of the mechanics with minor changes to allow for only 1 match. To not give players bounty progress for gambit-related bounties when playing GAMBIT prime is just ridiculous.
[spoiler]That being said I actually rather like Gambit Prime, although there are a lot of people using bots to AFK. I'm a bit confused as to how it can truly "evolve" though, but I'm excited to see what's coming![/spoiler]