So if the 319neo is nearly the same purchase price as an A321neo, do the professional fleet planners here think that the future will be B738s and A321s, plus the MAX 10 whenever/if ever those show up?

I think it's obvious the mighty guppy is the superior performer, I just find it hard to believe that we would be looking at a similar cost to operate a full A319 vs a B738 with only 128 seats filled. I understand the A319 isn't an A220 or E190, but there's gotta be some savings in fleet commonality. Then again, I'm not the expert on cost per seat gallon milage.

Is there any utility in a new A320 family purchase less than a 321 then?