50GB M-disc Blu-ray is a hell of an impressive archival jump to take (are you going to do something that expensive for every version bump?), I didn’t even know till right now that they’d succeeded in making double layer M-discs, much less in Blu-ray. I bet I’d need a newer M-disc burner to do double layer Blu-ray…
Edit: Jesus… they have 100GB M-Discs, too…