Bryan would have been squashed by Brock Lesnar and guess what.. fans would have been furious. They would have rallied behind Bryan to get the title back or get a proper rematch. Bryan would have gotten that rematch and have a great match with Lesnar. After that, who knows? One thing is for sure is that Roman wouldn't have been booed against Lesnar at Wrestlemania.
WWE would probably however do a Reigns vs Bryan programm down the line, and Reigns would start getting booed at that point. I think Bryan would have turned into something like Chris Jericho.
WWE would also try to turn him heel but that wouldn't work.
One thing is for sure. We would have gotten great matches with Rollins, Owens, Zayn, Styles, Nakamura, Balor. Bryan would turn into the main guy for all NXT alumni to face off against.