I'd love to get Replay Debugging [1] back... That of course was already gone in VMWare Workstation 8.

That was and still is a killer feature.

I know about rr and such, it's just another level to be able to record whole system state.

[1]: VMWare Workstation 7 demo about Replay Debugging: https://www.youtube.com/watch?v=YjZWn3iDPiM