What could have happened if the Beatles went on through the 70s and 80s?

I know it may be unfair and unrealistic to exercise this type of 
fantasy, but I often ask this to my Beatles fans friends. Of course, 
many of the facts in rock music after the Beatles, happened because of 
them (and/or because of their demise, one might say), but I always like 
to hear opinions.

Would they go the 'commercial' way? or what about prog rock? AOR? 
fusion? AM pop, soft rock? electronic music? how would they face punk rock?

Would they get into rockier sounds, with jams, heavy guitars, long solos?

Maybe politically correct and incorporating more and more third world, 
ethnical influences?

Or would they turn into something like the Rolling Stones, with the 
occasional sell-out tour and non-important records?

And finally, would they be able to keep their quality, still having 
commercial success and still being important to rock, and pop culture as 
a whole?

What do you think?

Rafael.