I think the BRS management team is one of the most able from a commercial standpoint with realistic expectations and in their master plan (detailed until 2015 and in outline until 2030) they say that there are about four long haul scheduled routes they consider viable from Bristol - New York (already flown), Washington, another US destination which they think would probably be Atlanta and Dubai.
The master plan makes great play about the B 787 being capable of flying these routes without load penalty, but that presumes an airline will fly to Dubai with a 787 sometime in the future and that it will also choose to fly from Bristol. BRS management says a runway extension is not necessary because it is believed the cost and environmental disruption would far outweigh any operational benefit given the type of aircraft likely to come into service over the next decade.
The master plan forecasts 120,000 passengers per annum to Dubai at 2015 growing to 140,000 at 2030.
Clearly Emirates would be near the top of their list because of its interlining capability but as Dubai's hedonistic attractions multiply who is to say it will not eventually become a destination with direct links from around the UK and elsewhere?
BTW, is the runway still slippery then? I thought that had mainly to do with the time it was being resurfaced.