In OTL, right before the birth of Rock'n'Roll, Polka music was coming back strong. The Polka revival of the 1950s would be a short lived thing, as Rock soon swept it from the airwaves. Your challange, should you choose to accept it, is to make a Polka-based form of music the dominant form of pop music during the later half of the 20th century in, at least, America, and maybe, the rest of the world.
And, remember,if you win, in Heaven there is no beer!