Had started around the same time as football, which do you think would be popular I'n this day an age 
Are you asking if MMA had organization and promotion in the 50's or 60's like football and boxing would it be more popular now?
I don't think it would make a difference, boxing peaked & MMA will probably do the same.
Yes, I see mma being more dominant,
personally i think MMA "HAS" peaked now....its getting very very polished and commercial, and the fighters are getting a bit like the premier league footballers.... oow i hurt my toe - fights off...
it will be all down hill from here ;)