This is a partially compiled list of just some of the routes that have been speculated by people on this thread and have come to fruitation/ confirmed to be launching in W17/S18. This goes to show that route speculation isn't all nonsense, even though I agree some can be quite stupid!
Luton-Tenerife (easyJet)
Luton-Stockholm
Luton-Dubrovnik
Luton-Marseille
Luton-Isle of Man
Luton-Florence
Luton-Valencia
Gatwick-Fort Lauderdale
Gatwick-Las Vegas (Norwegian)
Glasgow-Brussels
Glasgow-Madrid
Manchester-San Francisco
Manchester-Los Angeles
Manchester-Singapore (Direct)
Manchester-Seville
Birmingham-Valencia
Birmingham-Porto
Birmingham-Stockholm
Birmingham-Vienna
Birmingham-Cluj Napoca
Birmingham-Florence
Leeds-Newquay
Leeds-Berlin
Newcastle-Madrid
Newcastle-Gdansk
Newcastle-Warsaw
Aberdeen-Alicante
Cardiff-Berlin
Any viable and realistic routes you think could operate currently, please share!