This was posted on airliners.net by calpsafltskeds, whom I believe maintains the Google Docs page with UA fleet details. Not willing to guess on how accurate his guesses are, but he obviously has pretty in depth knowledge of our fleet.

"I'm guessing on the below fleet reductions upon service re-start:
319: hope to undo easyJet deal - retire 20 pre-1999 units, take newer China Southern units, cheap way to replace aging units.
320: retire 40 pre-1998 or 50 pre-1999 units
73G: retain these 1998/99 units - possibly sublease WN units back to WN for now to bring in some cash.
738: All newer than 1997 - probably keep until heavy checks come up like done with some 319/320 units
739: All are 2008 and newer except 12 2001 non-ER units. They were based in IAH and range limitations were workable. I'd store them until needed, doubt if they would have sales value. See below for more of my take on the 739.
752: Exit the 11 PW units now - Exit RR units as heavy checks come due. They might be able to provide more flights to Ireland/British Isles until 321XLR arrive, when they should be removed one-to-one with 321 deliveries. See if cargo market might make a sale of any 752s - if so sell any in fleet.
753: Retain these 2001-04 units. If Condor units become available for a song, pick them up.

763: Take 2 class units (1991-93) and move seats to 764 - as each stripped, exit the 763 units. The 2 class units can operate Transcons pretty efficiently. until seat removal, but may need to be stored until seats stripped. Keep 46J units (1998/2002) - flip a coin on N652UA (1992) in 46J mod and N674UA (2000) that is still Diamond seating.
772: Park 3 ER ITPE units, then convert to Domestic when 772As need removal due heavy checks. 772As are pretty efficient as mass transit movers for Domestic and Hawaii. Complete and retain all 772Polaris ER units
787s, complete Polaris program.
That would remove about 90 Narrowbodies and remove 21 older 763s (2 class and Diamond) from schedule right away, except maybe N652UA which is in High J Polaris mod.
That's about 110 mainline aircraft. If more are needed, then store some for now.

As for Express aircraft, there could be total turmoil with these carriers struggling to survive - TransState is out of business and all UAX units parked. UA may not have a choice on some Express operators, but voiding UA of all 50 seat units may not reflect demand problems. Also, scope issues may continue to restrict matching seat demand with express units.

The 739A non-ER units are all at least 3 years newer than the oldest 738 and a superior ride. They have 4 more F seats, 9 more Y seats and a mid cabin lav. With takeoff weights equal to a 738, IMHO I'd park them until demand returns, but would much rather retire older 2008 738 units before the 2001 739s. The only issue with the 739A is limited MTOW, which has been successfully handled by basing the aircraft in IAH. Otherwise they match the 739ER interior except they do not have power in Y, which is the same power as the 738 fleet."