I would be very surprised if 91131 doesn't end up in (painted!) Swallow livery when it joins the national collection. They're not gonna stick it in the grand hall of the NRM with peeling, faded red Virgin livery!
I could see AC loco group being interested in one, they have one of every other AC electric. Other than that, what would be the point of preserving any others? A 140mph electric loco is about as much use as a chocolate coal shovel on a preserved railway.
Other than 008 which looks to have a bleak future after having its nose cut off, with 20 locos being lined up for export and at least one due to be preserved, at least we should be spared from any mass scrapping of 91's any time soon. Given how things looked just a few weeks ago, I will take that!