Can't see it - think we'll stick with Kompany at 4th choice. When Otamendi, Stone and Laporte are all fit, Vinnie won't get any game time to be able to injure himself! I can see Vinnie just playing a cup role next season and he really should be able to manage that given the gaps in between.
Assuming we sign another DM option next season, Fernandinho is a more than capable 5th choice as well.
We should really be moulding someone for the 4th spot once Vinnie retires, not going out to market. We have potentially done that anyway with the signing of Philippe Sandler, who looks like he could be a tidy pickup. Give him another year on loan at a better club and he'll then be 22 and perhaps ready to take a spot in our squad.
If the club do feel like we have to sign another player, it will be someone like Evans, not one of the best CB's in the league - that ship sailed when we signed Laporte.
In any event, we're well stocked at the CB position for now in my opinion.