I also agree Riddler could be be pretty cool as a floorless coaster. At the same time, you'd think maybe B&M could use the vest technology to make a better, more comfortable restraint system for the stand up train. To me, the biggest issue with stand up coasters isn't the standing, it's the headbanging into the OTS.
I wouldn't really miss Scream all that much myself (aside from the Zero-G roll and the short lines), but if it did go, that's a pretty long dead end area to fill. I'd be curious what they'd put in there, if anything, because that'd be a lot of space going to waste. And I doubt they'd go back to making it parking again.