I agree with you 100% about ORD being the most likely next US gateway (though I have no idea where you picked the numbers for the odds). I sincerely hope it's UA and not LY.
I would add LY is most likely to start routes where AA or B6 have a hub.
AA hubs:LY isn't adding flights to AAs CLT/DFW/PHX hubs, not enough O/D traffic.
DCA and LGA are restricted from longhaul flights.
PHL is a long shot as it's so close to EWR/JFK that locals will just drive there and due to AA claiming failure there.
JFK, LAX, and MIA will all be LY served.
B6 hubs:
BOS and JFK are LY served.
LGB is too close to LAX.
FLL is too close to MIA
MCO is not enough O/D traffic.