This would be great news for Manchester which has the best domestic feed in the UK. Ok it might be a publicity play by Virgin but would certainly make sense in terms of feeding Virgin flight ex Manchester. As has been said peripheral routes may suffer. Doncaster and even Birmingham might be sweating if this did have legs. Virgin have shown zero interest in Birmingham which might lose yet more services.
I could also see the Exeter HQ shifted to Gatwick or possibly a domestic base at Manchester.