Harriers would be interesting, imagine the stunts they could perform with VIFF.
Not likely to happen though, maybe they'll use UAVs!

Get ahead of the curve.
In all seriousness though, the Eurofighter would probably be the best replacement, certainly the most manoeuvrable of the modern RAF jet line-up. A Tonka is a good aircraft but I don't think she could pull the moves that the BAe Hawk can.