The only possible reason I could see that they would ever consider to get rid of it would be maintenance cost. It's not like when the effects stop working on other rides. Because the attraction itself IS the effect. And there are a lot of effects elements that all have to sync together to pull off the illusion.
It has a relatively quick throughput, but one of the best designed queues, as the story-telling starts straight away it feels like you are immediately in the experience. And it's a rewarding experience too.
It's one of their best attractions in terms of execution. It's so unique in the UK, and so quintessentially Towers.
Because of it's association with the Towers, both in storyline and physical location, it's pretty permanently embedded into the park and it's culture. Obviously they can't relocate the Towers themselves lol (and there is absolutely no way they'd ever be permitted to demolish them!), and the majority of the attraction takes place within. The show building, which has a relatively small footprint, is located in a part of the park that isn't currently utilised by guests or other attractions anyway, and it's highly unlikely that they will be that pushed for sites for future developments that they would need to resort to expanding out to these areas.
It has the added advantages of being dry in the miserable winter months and cool in the baking summer months. And its also relatively calm and quiet in there too. Those sorts of things do make a difference to some guests.
All in all, I doubt it will be going anywhere anytime soon.