I'm pretty sure every patch until the first expansion is going to follow the same formula:

Even numbered patches:
ilevel cap lifted
New Coil turns

Odd numbered patches
New crystal tower

All patches:
New dungeon
2x hard mode dungeons
New primal
New trial that isn't a primal.
New main scenario quests.

The only surprise is which dungeons we're getting and which primal.

I do like your idea of a coliseum but it needs to be added alongside other content like dungeons and raids too.