It will probably be (i hope) a 9 episode part 2 with the current pacing of 2 chapters per episode, and what has been leaked, the 16 episodes will cover up to chapter 122, which means that part 2 will have 9 episodes which is perfectly fine because that's the same length as season 3 part 2 and it gives time for the director not to rush things
I initially thought that if i was levi i would choose erwin 100% but now that i think more about it, even though i think erwin is a greater asset than armin; mikasa and eren are much more important to eldia than erwin. Theres a high chance that if levi chose erwin, eren wouldve rebelled completely against eldia.