Who knows, but if there had been no pre-Revolver Beatles then they would have only had about a 3 year career. Their massive world-wide popularity was built really on all of those countless #1 hit singles from the early '60s, and the 100's of gigs they played and the TV exposure they got with all the screaming girls at the airports and Ed Sullivan and stuff. Plus, they never toured again after that 1966/Revolver period....and it's unheard of for a band to build any kind of global reputation and popularity without ever appearing/performing in public, so no, if nobody had heard of them before 1966 then in my view they would just have been viewed as an OK studio-session band who lasted about 3 years and who made 4 or 5 brilliant and interesting albums, and did a couple of movies.