If you look at aag practice, they have at least two different regional per hub.
So with if aa takes compass flying back and skw still in lax for aa it does leave an opening for a second regional in lax, the question is just who will it be.
Personally if envoy is in equation I would expect flying through lax more than a base there. If mesa cuts a deal with aa, mesa would be an option for aa in lax.
Just like everything in the regional industry, discuss all you want, no one will know until it's made public by mainline. There are at least 2 years to go for a decision on the lax rumor mill.