No details of course, and this is the first peep I've heard about it. 156ft is plenty tall enough to be a coaster. Seems a bit odd to try and stick another coaster in such proximity to Apollo's Chariot especially as FI is tucked into the corner as it is.
Also, the flat rides in Festa Italia are getting old (they're still impecably maintained though). The concept of a B&M flier swooping down over the Rhine River has always been floated out there, and the height of the proposed attraction would be pretty reasonable for a flier (like Manta, which only has a 140-foot max height). It's also a pretty legitamate height for a wing/4D coaster like Gatekeeper, which is just 170 feet tall on perfectly flat land.
Walt Disney World
Tokyo Disney Resort
Theme Park Insider Books