If he would have never retired in 1975, he would have gone on to win in 1976, 1977, 1978, 1979, 1980, 1981, 1982 and 1983. Lee Haney would have been TOO much for Arnold to handle. So in total, he would have won 14 Mr. Olympias in all.
A better question would be, if Arnold continued to improve upon his 1974 showing and not been distracted by Hollywood, what would he have looked like by the early 80's (he was only 33 in 1980)?