I give him one more season, maybe two with the condition that he has to move a core piece if they fail again this coming season. Dubas does have serious strikes against him (RFA contracts, not addressing the backup goalie issue properly for a year and a half), but he also has some big pluses - he actually made moves to improve our D and added two bonafide top 4 d-man - our D has gone from shit to solid under his watch. This current regime's picks outside of round 1 also look more promising than any of the Mark Hunter fridges that all pretty much busted.
That said, the RFA contracts are a huge strike just because it's backed him into a corner. Sure, he kinda got screwed by the pandemic and flat cap, and maybe this could've worked in a normal world, but he hasn't adjusted to the new reality - that stubborness can be blamed on him. And Keefe has looked overmatched in two straight playoffs now, and you generally don't get to fire a second coach that quickly (barring some Bill Peters like scandal).