Well... With all due respect you don't have a clue what would have happened with someone else, but I respect your conjecture. I'm of the opinion that the team really loved Schwartz and would have rallied around him as a HC. Thought it was quite telling how his guys carried him off the field in Detroit. Of course, whether or not we still would have got Tyrod or another QB, a competent NFL o coordinator, and all those other things are question marks.
What we do know is what did happen, which is that the Pegulas wanted to make a big splash with their first hire, got sold a bill of goods about "attitude" by Rex Ryan, and made that hire instead of rewarding Schwartz's success with a promotion from within. Instead, they got their big name, and he promptly took a top five 4-3 defense and drove it into the toilet in an effort to make it fit his "genius" defensive scheme.
Please fire Rex now.