If you'd like a nice, if brief, documentary on where the "Paul is Dead" myth came from, there's a Dutch documentary called "Who Buried Paul McCartney". I'll link pt. 1, and you can go from there.
http://www.youtube.com/watch?v=xqBf6iNPVOg
Overall, if Paul is dead, I don't expect the Beatles to carry on. It seems to me like there'd be a weight here added on to the other weights (fame, bickering, feeling like the band was dying already) that would just finally break the camel's back. The Beatles barely finished Get Back/Let it Be as it was (In the OTL, they pretty much abandoned the sessions and turned it over to various people who could take the scrap and complete something); this could see the project abandoned totally without any album following. Maybe some singles out of the finished material, especially related to McCartney's finished songs, but not an album.
There's an interesting side of this too, if I'm correct and the source I heard this from is correct (granted, its a "Paul is Dead" source, but there may be historical accuracy here): It's that, when people were told the rumor that McCartney was actually killed in a car accident,
a lot of artists released songs memorializing Paul McCartney because they thought he was dead, and there were blocks of programing dedicated to it for a little while. For example, Terry Knight's "
Saint Paul" (linked; this was actually released a short time before the "Paul is Dead" rumor took off). There's more than that; it's somewhere in the middle of the documentary "
The Winged Beatle". If true, that's a good indicator of the reaction you'd get in the OTL and it could balloon.
Another interesting side to this is how it'd meld into the "Paul is Dead" rumor where he died in 1966 if that rumor is out of the bag but still not mainstream; maybe some rationalization that all that happened, but the replacement Paul McCartney felt so guilty that he committed suicide or that he was going to reveal the truth but the others had him killed or something like that.