Sean - as in most things gca, I have everything to learn and little to add. But it seems to me that the fellow who became president of the USGA instead of CBMacdonald (was Roberston his name, in 1901 or 1902) was right from the start concerned about making sure that the American championship/open would be a true 'test' of golf. So, to answer yoyur question - no, I don't think that Augusta as a venue would've changed the par mantra; that had been, if not officially established/verbalized, at least in the air for 3 decades before Augusta came along.
Peter