(9/7/10) An interesting post has come up at Orlando United regarding the fate of Twister. It seems Helen Hunt was in the park not long ago and dropped in to check out the Twister attraction. At some point in the gift shop afterwards (while buying merchandise) she mentioned that they were preparing to make a sequel to the first film, but the new one would be in 3D. As such, Universal may end up keeping Twister around long enough to take advantage of the hype from the new film and even upgrade it as well.
This rumor was too good not to share, but take it with a grain of salt.