Well, there's going to have to be some kind of late night weekday news output, but I suspect that Newsnight as it is, won't be around for much longer. As a programme it is a very damaged brand, and this might be the excuse they need to overhaul it.
Strangely, I forsee some kind of 11pm BBC Two/BBC News Channel simulcast, with a programme produced from Studio B, much like Newsnight itself, but with a totally different name. Probably an hour long programme.
ISTR, though someone please correct me if I'm wrong, that the Ofcom requirement is for the 'big 5' channels to air at least 30 minutes of news between 6pm and 11pm, meaning that there would still have to be some sort of news programme at 10:30?