If you are going to do LH out of LHR you still need feeders, no other carrier has a feeder to LHR from Belfast except bmi (who funny enough have made links with the exBMED/BA network!), EI broke out of the one world agreement with BA and others, they are pitching at the loco market which I think would do well however I dont think the price added to tickets for connecting flights out of LHR would be much different than what EI would charge, but with no through baggage check-in or IATA cover i.e. collect your bags and recheck in at LHR and no transfers to the next onward flight if delays are incured, I think its a no brainer!
I agree the later BFS flight would benifit Pax in NI but without going into the " mines bigger and better than yours" we all know the story of the teddies being thrown out of the cot some years ago causing the move to BHD thats not to say things may change!
The shorthaul will be feeders in to LHR with onward connections but will still maintain a product for the business traveller who stop at LHR.
At a guess bmi will end up with 5 or 6 domestic routes to LHR of which one will be Belfast.
That also doesnt rule out these routes originating from LHR(Doh can of worms opened!).
rgds
Keepitlit