I doubt they ever release 5DV. I'd be very interested to see it but I doubt. I think we've already seen all the best and the last full frame DSLRs from Canon. That's enough for smooth transition to the RF mount.
A lot of people still prefer looking the optical viewfinder (again, just look up more interviews about where they tell there is still demand for DSLRs), and the 5D is an important 'iconic' product line. They've already developed some things for the 1DX III which is not going to be their biggest seller, why would they just throw that right away.
The EOS R5 is filled up with techology, but it still does not look as durable as a 5D, so there is certainly a place for it. They just don't need to rush it, which will instantly make people think that they are killing it.
The 6D line might be coming to an end however, seeing how little the D780 has changed, they can certainly top that with a mirrorless camera.