I'm sticking to my original guess. Six Flags is bringing back a historic ride with a modern twist. All their hints on twitter have had "#ACEOnline" plus the original Rockville Realty announcement mentioned "Division of ACE," and, "History in the making." ACE is dedicated to the preservation to classic or historically significant roller coasters.
But Six Flags isn't- or should I say wasn't- known for taking great care of wood coasters nor are they known for restoring old rides. That ended until their relationship with RMC started, as the refurb of the Rattler is incredible. And so it's no surprise then that Six Flags has hinted, not subtly, about more work with RMC on this ACE historic project. Recall the numerous more recent clues about "wood", "steel", and MK Bozer's announcement of tending to a "snake problem" in Rockville after working on all the other RMC projects.
Whether it's a new layout or not, I don't know, as they could be building a loose recreation of an old ride (like the "Airplane coaster) or, less likely I think, buying something used and retracking it with steel. Now that Six Flags is throwing around the 120' height, the Cycline from SFNE is a possibility.
What's more, having a historic wood coaster fits the Rockville 50's-era theming.
All the clues fit this, do they not? Sure, the park could be deliberately misleading everyone, but what's the point of guessing if one isn't going to at least follow the breadcrumbs presented?