At the DH World Cup in Maribor, Slovenia, Loris Vergier and Greg Minnaar are running unmarked derailleurs that look quite different from the current Shimano Saint M820.
Shimano's Saint components have remained largely unchanged for the last 7 years, a testament to how refined the parts where when they were first released. However, given that the XTR, XT, SLX, and Deore drivetrains have all recently received significant updates, it would only make sense that the venerable Saint group would be the next in line for some revisions.
The most noticeable change is the shape of the parallelogram. The distinctive X-shape of the current version
is gone, replaced by a rectangular piece with more material in the center. The entire derailleur looks more compact, which could be a sign that it's now designed specifically for downhill cassettes with 7 or fewer gears – the original was designed to work with up to a 10-speed cassette. The derailleur also uses a standard mount, as opposed to the direct mount compatible design used previously.
The adjustable clutch mechanism hasn't gone anywhere, and like Shimano's other derailleurs a lever is used to turn it off to help with wheel changes.
Loris was using an XT shifter to operate the new derailleur, but there's likely a new shifter floating around somewhere too - we'll see what we can dig up.