Jetmonkey says:
"As far as the wides go, I see all of their 76's being parked around the same time as ours and all being replaced with the 330's LCC has on order. I see them keeping all the 75's for some time just as they have mentioned for ours as well. UA has quite of bit of them, and there really worth their weight. I would venture to believe that all the 74's would eventually go as well, being replaced when the 350XWB come on line. And if the plane performes well enough I can see more being ordered for us. So in the end you can see a new United with a mix of A350's, 777's, 330's and 75's for the time being. And the rest of course will be a bunch of 319's, 20's and 321's. But this is just IMHO. I've been wrong before."
United has about 35 767-300s, I think. UA does not operate 67-200s for almost 6 years, they parked all 9 in the desert after 9/11. They sold 8 of the 9 200s last year, (they still have one out there, the tenth 200 was lost on 9/11.)
I believe US Air flies 200s with completely different engines from UAs 300s. The 200s and 300s at UA could not swap engines and probably the 200s from US Air can't either with UA's 300s and are similar to the old UA 200's: Smaller and inefficient gas guzzlers.
UA's 300s are not the latest thing anymore but they are not even close to retire them as of now. As a matter of fact all 300s MZ, with the exception of the few 300s MD with the domestic configuration, are being refitted with new First Class and Biz class suits. First Class will go from 10 seats to 6 suits and B-Class from 32 seats to 26 full liedown suits. There are already a few flying in between IAD and Europe, (ZUR, etc,) and all f/as are doing, (should have been done by now,) the FAA mandated qualification for the new 767 configuration which has been designated MI.
By the way, they also reconfiguring the 400 cabin at great expense, which is designated OC. FAA has finally approved the 400 new cabin config, after it failed initial evac testing. All F/As are now doing the FAA mandated requal for the 400, computer based with the additional FAA mandate of hands-on training because of the evac testing failure. We did not have to do hands-on for the new 67 cabin reconfig, only computer based FAA mandated training.
(If you like to know: United has about 30 active 400s. I believe they have 2 in the desert. One was delivered in 1992 and stored in 2001, the other delivered in '93 and stored in 2003. Why, I don't know. Maybe they were leased and UA could not renegotiate the terms during BK? Maybe too expensive to get them back in flying condition?)
So, your prediction of UA's 67 and 400 demise, although possible, is way out of sync with the present reality. Weird things happen in this industry but qualifying almost 16k F/As on 2 models, (the 777 will be next,) reconfiguring the cabins on the 67 and 400 fleets, and then parking those planes?
Again, your prediction doesn't come close to the present reality, and you probably wrong again.