Its blatantly obvious that the Grand Priest is the final villain (has been obvious since the Zamasu arc)
Hes able to see whats going on in every other universe (like when they got 10 members he knew right away), meaning that he probably knew about Zamasu and the travelling between timeline shyt which is illegal but for unknown reasons he didn't punish Universe 7.
All the other angels are probably in on the plan that the Grand Priest has and the final arc will probably involve fighting the angels. Look at U9's angel smiling as his universe is destroyed
Im still 50/50 on Whis being involved with them
And if we really look at the dynamic its clear to see that both Zeno's kinda take orders from the Grand Priest. Hes defo exploiting their childlike nature for reasons that will be revealed soon