Th13teen and the smiler, although most recent, have had the most problems,both are fairly unreliable, both are easier to remove than the rest (on fairly flat land) and B&M tend to last a long time (am I correct in thinking no B&Ms have been scrapped?) Thirteen is a prototype and the smiler is 2 and while a great coaster, has had loads of problems, is rough, won't be as popular when it re opens probably and has a chance (although a tiny, tiny chance) of being removed. Gerstlauers tend to have shorter lifespans though. If another coaster in England breaks the inversion record (unlikely but in China golden horse designed a ride with 15 inversions) it will lose more popularity ( I see its record being beaten in 15 years, Nemesis I don't think will go until it's past 40, and Oblivion is not worth removing with the majority being underground, quite hard to remove. Rita will be the first thrill coaster to go, but then again it's not a Secret Weapon. The smiler and thirteen, relatively easier to remove than other SWs. If Nemesis and The Smiler opened in the same year, and both ran for 5 years, the smiler would be more popular due to it breaking records, 10 years, Nemesis would be more popular, due to it being better quality, and less gimmicky, more reliable and generally an all round better ride.
If the smiler re opens, and it has one more incident where people get injured, it will be gone, although I doubt it will injure anyone again, so many safety precautions will be put on it. The popularity of it was starting to decline at the start of the season, it was getting less queues, and then a fair bunch of people will have been put off. While I would hate for any of them to go, I think the worst impact would be nemesis, the smiler people would see why, but Nemesis, without an incident, would have a terrible impact. Just think at the impact corkscrew had when it left, and that's a standard, rough Vekoma corkscrew, only exception being it brought the theme park properly into the UK. I'm thinking the smiler or thirteen will go first, then Oblivion, then air, then Nemesis. I can't see any going until we have SW10, and 12 coasters, with SW8, 9 and 10 possibly being coasters, 9 will be enough. I reckon all coasters have a life span of 2025 at minimum. Plus if Nemesis went, I would cry