Lovely dream** saudade**; sure you weren’t channeling? 
I thought about that last night, watching a somewhat chunky wattled McCartney on stage. My WAG would be that those two might have gotten back together for a song or a project, but probably not as the Beatles. First off, Harrison wouldn’t want to be part of it. He had all the Beatles he could stand, thankyouverymuch, and he wouldn’t see the need. Ringo would go along with it, since he’s appeared with Paul on some things (“Take It Away” for example, with George Martin in the video playing keyboards).
There’s a lovely story Paul tells about the time on Saturday Night Live when they offered the Beatles something like $1,500 to appear on their stage. Paul and John were in New York watching that night, and they thought it would be a lark going down there and collecting. They went down to catch a taxi, and by that time the joke wore off and they ditched it.
I remember the huge fuss that erupted over just the rumor that “The Beatles would reunite!” which probably did the most to ensure that they never would. Why let themselves in for that kind of shit: going up there, rehearsing for a concert, giving it, and being told “awww, you’re not as good as you used to be!” Who needs it?
What also helped kill the Beatles was a limitation of imagination, in that it always appeared that they either had to be in the band, or not. Nowadays, you’d have artists going off, releasing their own work, then coming back into the group (Mick Jaggar, Phil Collins, KISS come to mind immediately). The Beatles didn’t seem to have that option, and made the splintering all the more permanent when it came.
So the Beatles wouldn’t have been reformed, but it would have been possible for Lennon/McCartney to show up again, either for an album or just a song or two. Their friendship would have survived.