I think this is pretty obvious:
IAH and ATL stay at current levels,with perhaps some CO 737s and new 757-300s moving to ATL and some DL domestic 767s move to IAH (to spread things out and rationalize things a bit).
IAH has more room to grow with CAL's new International Terminal E in the works (2002),and a new runway under construction.I would look for continued expansion South from there and new European flights like Frankfurt,Madrid,Rome and Amsterdam.Partner airlines like Alitalia can add new services like Milan.
ATL has more room to grow South into Mexico and the Carribean.
As for NY,EWR and LGA will be the focus with JFK being divested to perhaps NW or even AA.CAL is in the middle of a huge capital expansion at EWR.DL proposed a new Terminal project at JFK but never approved it.
JFK might have more room to grow but EWR is all ready to go,and many arguments can be made that EWR is just much more conveinent than JFK.Thats one of the big reasons for a CAL/DAL link up,to maximise EWR's potential.
CAL has the big international routes already set up at EWR (NRT,HKG,GRU,EZE,LONDON! etc..) and the domestic feed,while DAL has the secondary European cities like Lyon,Nice,Barcelona,Venice,Istanbul and so on to add.Plus DAL has the widebodies CAL desparetly needs for international and trans-con flights.
The EU and the DOJ will not let CAL/DL control EWR,JFK and LGA with all those international flights.
To get this approved they would have to divest JFK to perhaps NW who already has a NRT flight from JFK and partner KLM to work with.They (CAL/DAL) can divest the JFK routes that overlap with EWR's like Frankfurt,Rome,Milan Paris and so on and keep the ones that don't like Istanbul,Athens etc.Plus they can add CAL's DC-10s to the deal so NW can operate the JFK hub while waiting for their A330s to arrive.
EWR would not be a RJ hub,all RJ flights would be moved to LGA.The smallest aircraft based at EWR would be a 737-500,this would mean less frequencies to places like Rochester but more seats and the comfort of larger aircraft.
LGA would compliment EWR with short - Medium range flights.
SLC would remain at current levels,but CAL/DAL would have to develop a West coast presence,which they can with all the RJs they both have on order.
In Ohio thats the tricky part,if the DOJ will let them they can run both,of course CVG will be bigger but CLE has a decent business market which warrants alot of O&D flights.They can intergrate Comairs CVG ops with COEX at CLE,thus providing a nice Mid-West RJ network that makes sense.Plus CAL/DAL can continue main line jet flights to BOS,LGA,DCA,MCO,LAS,LAX,SFO and where there's demand.And the CLE-LGW route is another business route for the City.
If the DOJ will not allow a CLE and CVG hub than HP or someone else would love to get into either hubs.
DFW is another toss up with regards to the DOJ,but I think with the new longer range ERJs CAL has on order which can fly 1500 Mi +,and DFW being a strong business market I think they too can continue to operate a small business oriented hub with main line flights to BOS,LGA,DCA,LAX etc. and RJs to AUS,SAN,OKC and so on.
And with the demise of Legend,DAL (Love field) could see some business oriented RJ growth.
Eastern Air lines flt # 701, EWR-MCO Boeing 757