I think short haul growth will come from EZY mainly, with more from TOM and TCX. FR is a strange one. I can't see why they aren't expanding at BRS given the rate of expansion of EZY and other carriers. Personally I think they are missing a trick, but they obviously know more than I do!
New foreign carriers don't always seem to do that great at BRS. LH and AF didn't last, SK couldn't even make a summer seasonal route work, Helvetic, now possibly WOW not returning (s18 TBC) CO had it's own reasons but BRS market was apparently part to do with it, Wizz seems to have stagnated, although I hear whilst the route frequency for S18 will be the same, some of it's routes will be operated by the A321. Some of those are big players in the EU market, so unless there's an untapped niche somewhere, I don't see any major surprises looming.
I can't see EZY going anywhere anytime soon, so maybe a large proportion of the eggs in the Orange basket isn't such a bad thing.
If BA did well this summer I can see more comings from them, albeit limited to suit the LCY ops.
Monarch or Jet2? Would be a great fit, but are they really needed?
I think that you are right about most of the growth continuing to be provided by easyJet, TUI and Thomas Cook, although Ryanair have been increasing their offering in winter substantially both last winter and the forthcoming one. Summer though seems to remain flat for the most part with Ryanair. It's possible, perhaps probable, that easyJet will base another aircraft at the airport next summer as they have been doing in recent years, presumably part of the five-year agreement with the airport which must be coming to an end soon.
The reasons for some of the overseas carriers not sticking seem to be varied and not always self-evident.
Continental lasted five and a half years from May 2005 until November 2010 and came to BRS at the time they had no access to LHR. Within two or three years they did gain access and promptly switched their LGW-EWR route to LHR. From then on I always felt that BRS was on borrowed time and said so more than once on aviation message boards long before the axe fell. Why operate 4 x daily from the mammoth LHR with a fifth daily at a small airport 100 miles down the road? It would make more sense to operate all 5 from LHR, which is what they did. They must have had slots or were able to get them for the increased LHR frequency.
Lufthansa to FRA was operated by Eurowings Bae 146-300 aircraft 3 times daily (21 x weekly) from the beginning of the summer 2008 season. Loads generally averaged around 60% on the 100-seat aircraft but 3 x daily was really too many seats. Within the first six months LH announced that BRS-originating passengers had used every one of LH's long haul routes out of FRA. Winter 08/09 saw a reduction in frequency which was a positive move bringing seats into line with the market. After a year LH suddenly pulled the plug - I know from speaking to a senior person at BRS closely involved with route development that the move came out of the blue (an early morning phone call from the LH UK chief) as LH had only recently told them that they were pleased with progress - 100,000 passengers in the year of operation.
This was at the height of the recession which was the culprit. LH intimated the route would be back and it was thought they were getting ready to use bmi regional which they then owned. bmir was sold and the new owners operated to FRA which LH soon joined as a code share (as they did with MUC) which remains the current situation. 3 x daily on a 50-seater is a good schedule although bmir's owners have stated publicly that BRS-FRA is a route they would use larger aircraft on when they get them.
Helvetic
Initially operated ZRH-CWL with F100s. Loads were poor so BRS was later included as a double drop with CWL. Eventually CWL was dropped and the route operated between ZRH and BRS. Loads improved to the point of a monthly 65% load factor but that wasn't enough and Helvetic eventually pulled out. A senior person at BRS told me they tried to get Helvetic to increase from 3 x weekly to 6 x weekly as this sort of schedule would enable them to link into the Swiss network. BRS-ZRH seems a glaring omission from the BRS route network.
Air France
In the 1990s Brit Air operated F28s for Air France on BRS-CDG. After they pulled out Air France returned in the early years of this century in the guise of Air France Regional with E145s at 3 x daily against BACx (later BACon) also 3 x daily with similar aircraft. That operated for a few years then when Flybe took over BACon in 2007 and axed all the BRS BACon routes it looked as though BRS would have no CDG route.
easyJet stepped in then a year or two later Airlinair came along as 'Air France' with an 18 x weekly ATR 42 (later upgraded to 72) service. Four years ago they began to reduce the service, replacing it with a daily Air Hop! E190 which was often replaced by a CityJet ARJ, before pulling out in 2014, by which time the KLM AMS route was being increased to 4 x daily with E190s, indicating that the combined AF/KLM Group was going to concentrate on AMS as their gateway from BRS.
SAS
First came with a limited 8-week season in summer 2007 to Stockholm Arlanda at 2 x weekly with Boeing 737-600 aircraft from mid-June that year. This was repeated in summer 2008 with the addition of a 3 x weekly Oslo service for the entire summer. Prior to summer 2009 SAS went into near financial meltdown and axed 40% of its route network, including those to BRS.
In summer 2014 SAS returned on the Stockholm route for an identical 8-week season, again with Boeing 737-600 aircraft. It was heavily advertised as a tourist route at both ends. The route again operated in similar fashion in summer 15 but failed to return in summer 16. Quite what SAS expected from it I don't know. Load factors were around the 90% mark and fares certainly weren't cheap. It will be fascinating to see how easyJet copes on Stockholm when it begins later this year.
WOW
Never seemed fully committed to BRS and the BRS route seemed to be the one to suffer when weather or aircraft problems came along. Last year there were a number of occasion where delays amounted to around 12 hours causing passengers to miss their transatlantic connections. WOW then took a complete break after the winter season this year until June. It's little wonder that some passengers became wary of booking with them.