Seems like quite a few great musicians and songwriters have worked with Vince over the years, but there is still one person in particular I would LOVE to see work with Vince and am surprised Vince hasn't worked with him yet. That person would be Mike Nesmith (yes, of former Monkees fame) who is an exceptional songwriter in his own right and after the Monkees show went on to write and produce and had his own band and is a pioneer in development of the music video. It has always struck me that some of his best songs "I've Just Begun to Care" and "Born to Love You" immediately come to mind- would be great to sing as a duet with Vince Gill, and would once again bring Nez' great songwriting talents to the public forefront.
If anyone could coax Mike Nesmith out of his self imposed semi retirement I would say it would no doubt be Vince Gill, who I know grew up watching "the Monkees" on TV (I saw the Q&A on YouTube where Vince said he had their poster on his wall) and no doubt has tremendous respect for Nez and his music. Since Vince works or has worked with just about everyone I would say it would be great to see these two on stage together....also they both have that great sense of humor about them.