How about Flair? Remember they tried to recruit Shelton into Evolution so there is a little bit of history there. Shelton could come out donning the Flair robe like AJ Styles did. Unlikely though, more likely we would see him paired with Teddy Long.
There have been some rumors on here about the WWE bringing back some former employees within the next year. I personally would love to see Heidenreich back in the WWE because I though he was very entertaining during his first run. He went through his heel/face time and his serious/comedic time when he was there and I didnt hate it. There is also people now I can see him having great feuds with.