I think at this moment, it will all boil down to three things:

1) What Masked Carnivale rewards, what is the incentive and replayability? Will we be able to farm relevant tomestomes in this content, for example?

2) Will Masked Carnivale be a fun activity in general consensus or a chore, like Eureka?

3) They intend for Limited Jobs to have some sort of limited "endgame" play too. But they will keep that updated with new features every patch?

Overall, the feeling is that this is a huge "test-drive" aspect. And maybe, depending on player response, they might really turn BLU into a support ranged caster unit by 5.0. To answers their worries about "not bringing the right abilities", just lock endgame duties to a certain Blue Magic collection with the main tools for dpsing, and some supportive spells.