My only concern is Flybe could lose out quite significantly at SOU if the BOH base 'dilutes' their routes too much. Currently they offer quite good frequencies to most major domestic destinations as well as the Channel Islands and the likes on DUB, AMS and ORY, which for some makes it a good alternative to trekking to Gatwick or Heathrow to fly to those places. If a frequency were to be lost in favour of duplicating the route at BOH then this could make the existing business routes less attractive to these passengers.
Having said that I guess a single frequency from to AMS/DUB/ORY/CDG/BHD and maybe a combined GCI/JER like they do from EXT could cater well for primarily leisure travellers and could probably be added without diluting the routes from SOU too much. As for domestics I could see a couple of flights a day to GLA/EDI and a couple to MAN, mainly to connect to the 'hub' there. Finally Flybe should be able to make a good go of a few regional French routes from BOH with smaller aircraft, as Ryanair have already tried and dropped the likes of NTE, LIG, MRS.