Responses from Rocky Mountain & Commencal (Updated January 10, 2022):
Vancouver's North Shore is the infamous proving ground for prototype bikes with its relentless rough and steep, technical trails. In the late 90's, The Shore opened the eyes of bike industry brands to how weekend warriors were torturing frames and components in these deep dark woods, so it's no surprise that unmarked bikes still lurk around trailheads.
North Shore local shredder trail.mole
posted a 2021 recap video on his Instagram account and in the opening shot you can see a naked aluminum high pivot prototype frame, complete with an idler pulley and low linkage-driven coil shock. The bike surely has two 29" wheels and a burly fork, but it's not a DH bike due to the size of the cassette, at least in this configuration.
From the pixelated mess it's unclear whether the bike is a high single pivot (HSP) or a virtual high pivot, like the Norco Range. However, one might notice a small black dot adjacent to the rear axle, leading us to believe that there is more to this proto than just an HSP design.
Our best guess is that it's a brand with ties to the Pacific Northwest that has the manufacturing resources to tinker with such theories, in particular, Rocky Mountain. The Slayer is on its third year of production - a typical time for frames to see a revision. Trail Mole also tags Rocky Mountain Bicycles in his Instagram posts, which leads us to believe it could be a creation by their R&D team. Plus Transition, Norco, Devinci, and Evil have recently released new long travel bikes, so that would rule out any immediate changes to their line ups.
It could also be the reincarnation of the Commencal Supreme SX, since their Canadian office is located just up the road in Squamish. Commencal's latest prototype Supreme DH uses a virtual high pivot, but doesn't allow for the full insertion of a dropper post due to pivot that passes through the seat tube. Similar to the Norco Range, this could be a way around the seat tube interference while still allowing for tuning the braking forces independently on a high pivot design.
We've reached out to a few of these brands to ask if they can give us any information about a potential new frame design and will update this space with responses.