None of the answers to your questions are definitively known yet.
The devs have described the new raid as the tank takedown and you can see snippets of it in the trailer video:
https://www.youtube.com/watch?v=G5CSyebsgpQ
Datamined info shows some stuff about Grevious, droids and tank abilities but as with the datamining on Rancor, it will likely change substantially before release.
It hasn't been stated that the rancor raid will go away - it seems unlikely as people are still trying to get Han Solo shards and there looks to be plenty of slots for various raids in the raid menu.
There has been no news of a level cap raise (though plenty of baseless speculation from players).
