Anything could be removed in the future. Everything has an expiration date. That list doesn't necessarily mean anything in particular - it's just another example of him trying to be coy about the rumors he thinks he's picked up on. Obviously though we will eventually see a lot of things be replaced and/or phased out. It's been a topic since this site started that a lot of stuff is has been simply wearing out and it's not as simple as just replacing it with all the new ADA standards and custom parts and whatnot.
Just off the top of my head, there are five major development areas I've been expecting work to be done on at some point:
1. Midtown area with the tree house and what's left of the landing area. Also probably Grandfather's mansion.
2. Old waterboggin area and nearby pathways
3. Powderkeg/waterfall/Opera house queue area.
4. Riverside theatre and the empty space next to it.
5. Entrance up to the hospitality house
That's a lot of area development potential right there.
Then you've got FiTH, FM, Grandfather's Mansion, and American Plunge which all have their issues and inevitably need to be reworked or entirely replaced within the near future. FiTH will probably get the RMC treatment that Blazing Fury got, Flooded Mine will probably be reworked to some degree, Grandfather's Mansion will probably close for good (perhaps with a minor replacement in the same spirit?), and American Plunge will probably make way for a new water ride. Wouldn't even try to guess the order or timeline of all that though, it's just what I've always seen as inevitable. Enjoy it while you can and get excited for the next thing!