Not sure how this is going to work. Vince Gill is actually a great singer, in the country music sense, but he has a high voice which would be more suited to the Randy Meisner/Timothy Schmidt role, as opposed to singing Glenn Frey's parts.
What I'd really like to see - if they insist on keeping the band going - is the return of Don Felder on guitar... since Frey seemed to be the one who wanted him gone and now that's no longer an issue.