In general, someone would have come in and created a business model for gca similar to RTJ.
Specifically, I wonder how Dick Wilson's designs might have varied. He came from the Merion/Flynn mold, but the characteristics of his work seem to be more based on competing with Jones. More difficulty, less subtlety, etc., rather than carrying on a less bold, more subtle Merion/Flynn style. Might have had a different effect.
Who would have remodeled Oakland Hills, taking over from Ross when he passed away, after drawing a plan (which, BTW, wasn't all that different than the final Jones plan) Did RTJ influence the USGA in course designs for the Open or was it the other way around, and the results would have been similar, setting a slightly different path?
And, of more personal concern, how much lower would design fees be today if RTJ hadn't set the precedence for signature fees?
(And, I actually recall he was the prime mover in the long discarded ASGCA standard minimum fee schedule......)
Fascinating to speculate how things might have gone, a la "Back to the Future." Also impossible to know.