Virgin will be offering 8 return flights. This was announced a few months ago.
I can't see there being enough demand for Thomas Cook and Virgin though. This year so far there was around 10 flights..
Go back 10 years, and there were about 3 flights every weekend out of BFS to Orlando, all through the summer. Add in the 'halo' effect that flying directly from BFS with VS brings, and I don't think we'll have any problem filling these flights. With A330s available, VS can be flexible with capacity too. I wouldn't be surprised if they throw in the odd LAS trip as well.