Spoken as a Boeing guy, I'd prefer a 320/321/350 mix for everything if fleet commonality and strealined training paths were actually a thing. I think the 321 NEO and 350 both work very well in their respective roles, as probably will the 777-X. The 737Max is a sad answer to the 321...it’s an aeroplane that has roots that go halfway back to the Wright Bros. Lots of lipstick, but still a pig.
Whatever they decide it will be at odds with the hopes of at least half of us, it will be too little, and it will be too late.