A few thoughts:
1) Remember when Universal cheaped out during the initial construction of Shrek 4D, basically just retrofitting the Hitchcock preshow room and 3D theater? The Psycho theater and post show exhibits mostly still stood behind closed doors, mothballed. Only after the attraction garnered massive wait times given its popularity, proximity to the entrance of the park, and relatively low capacity with only a single theater did they bother tearing out the rest of Hitchcock and building an identical back theater. They even removed Universal Express while the theater was under construction to help alleviate wait times! All for what's, in my opinion, the absolute weakest major attraction in the resort.
2) I doubt they'll do this, but Hollywood just upgraded their Shrek 4D preshow with a Donkey puppet (animatronic)? that does the safety spiel before the pigs begin talking. It'd be a neat addition in Florida, but perhaps a little redundant when Donkey has his own popular meet and greet across the street.
3) People who think this building is small are deluding themselves - it's quite a sizable space, and with two large theaters they could fit in something pretty sizable if they wanted to. They won't, but there's nothing saying this space can only hold a 3D theater (or two).
4) People keep bringing up the whole advertising thing with Shrek - while yes, he remains a popular and relevant brand (especially with foreign audiences, from what I can surmise), you have to also remember that Universal maintains a proportional advertising agreement with Dreamworks, not unlike the agreement Uni has with Marvel. In short, a certain percentage of Universal's advertising *must* include Shrek and pals - I believe there may also be an agreement to have X% of merchandising space devoted to Shrek in the larger stores, too. Someone please correct me if I'm wrong.
5) Terminator 2:3D still impresses the hell out of tourists. I recall bringing a friend's family a few years back who had never been to Universal, and the mother (who LOVES coasters and thrill rides and enjoyed pretty much the entirety of the parks) felt it was the strongest attraction from beginning to end and made a point to see it again later in the trip. We may be used to the whole motorcycle in-and-out of the screen schtick, but average joe tourist has never seen it, and it's still remarkably impressive decades after its debut.
6) That said, I totally could see the argument that it's garnering minimal merchandise sales: Terminator just isn't a very relevant brand anymore, and I don't see the new Genesis film revitalizing it much. I think the attraction's days are numbered, though that space is on the smaller side... not sure what they'd slot in. I'd really prefer they shore up other weaker areas of the park (Shrek, Fear Factor, Twister, KidZone), but that probably won't happen.
7) Twister should've been gone yesterday. It's a nifty effects showcase but overall the attraction doesn't do anything that Disaster doesn't really do better and the film, and its stars are laughably irrelevant to anyone who isn't in on the Bill Paxton jokes. The show also just hasn't been as good since they've gradually toned it down and let effects fall into disrepair. On top of that, I suspect its merchandise sales are awful, cow or no cow. I welcome a replacement.
8) Though I believe Disaster is mechanically in dire straits (remember that abrupt, unannounced three month refurbishment a couple years ago?), it would be a real shame to use it. That's a huge tourist people pleaser and a really entertaining, well-written attraction through and through. The effects tunnel also still impresses me, even after 25 years of exhibition. It'd be a shame to lose it with so many weaker attractions still standing. That said, if they are forced to close it due to irreparable mechanical failure, Creative will need to scramble to put together a replacement - that area's prime real estate.
9) I'm very pleased that ET Adventure seems to be safe for the foreseeable future, as it should be. I just hope that while they were fixing up the names database system they noticed how musty the actual ride experience has gotten and have budgeted a cleanup/upgrade or two.