Captinbirdseye,
A new dawn hopefully indeed.
As for long haul, really depends who takes the airport on I suppose as to what will change, whether the new operator has existing relationships with the right airlines etc. I wouldn't expect much in the way of long haul though, the USA is virtually out of the question. New York is the obvious destination and airlines seem reluctant to operate there away from LHR, even LGW is down to bare bones now on other routes. The most feasible that could be hoped for is Emirates or Etihad I guess, perhaps the odd niche player or start-up like United Airways at LGW. Personally, I'd just be happy with securing Air Asia.
What I think will happen is some escapees will return, such as Norwegian, Blue Air, maybe El Al. Anything else is anyone's guess.