Its already 72k compared to BB5s at like 7k.
BB6s already lose more credits than gained when the sink. Unlike 5s which can still gain 1k credits when they sink. Right now its impossible to continuously play a BB6 (Unless owning harbor for that nation) without some kind of income.
A proper PCV can hold itself against a CV6.
No Rec.
I'm all for making end game content only for End Game Modes (Fleet War, Normal Room, HA)
However, this would cause issues of players in HA not having practice in their 6s when they get a new 6.