Some would only fly ETO. Some would only fly PTO. Some would rotate through so as to fly all the planes.
Removing squads from the picture....
I see people gravitating to the arenas where most of the rest of the players are. So if Eastern Front, LW is filling up that is where others will flock to. So instead of having 2 large arenas full of everyone doing their thing we will have one large arena and several empty ones.
As soon as you then start imposing caps in that arena, someone isn't going to be able to fly their favorite ride and get upset. And they WILL have caps or a large portion of the player-base will gravitate to one arena because of the herd mentality.
That said, I'm willing to try it

But if I can't get into one arena where I can find decent fights and the others are empty I won't have fun. Its hard enough sometimes now in GVs...