I think a game mode doesnt even exist anymore

That's a self-inflicted low priority queue.

Featured game modes only last for a few weeks, then they're replaced with other ones after a little bit. Don't worry, there's a new featured game mode coming out later this patch :) /s

Seriously though, why does Riot even keep up the ruse? Every reason they give for keeping Featured Game Modes temporary could apply to Dominion at this point.

Dominion Draft is pretty much dead. Riot talked about disabling it, I'm not quite sure why they didn't. Queue for Blind if you want to play Dominion, or play in a tournament, if NA has any (as far as I know, they don't at the moment).