If I may do an Ultimate Coaster-style response throw back for the older CFers in the room:
Yes, Kingda Ka being removed would be because of new site prep needed for a new attraction.
Not as much as you'd think - relocations typically hover ~$4-6M depending on size and scale, which is still at least half the going rate for new coaster installations of similar size ($12-$15M). Let's not forget Green Lantern itself is a relocation, done on the same merit.
You say that, but I would gladly bet there are many second and third-tier Cedar Fair and Six Flags parks who would gladly raise their hand for a large footprint B&M. (e.g., Worlds of Fun, Valleyfair, SFStL, La Ronde, Canada's Wonderland, Kings Island, etc.)
It's undeniable the amount of things that could be done between the adjoining Green Lantern and KK plots (and Golden Kingdom zoo area); but I still expect there to be some holdout to see if a KK 2.0 could be doable.