My hypothesis is that the new free episode is a prototype for a new game, which would explain why it wasn't just a set of levels, but a testing ground for a lot of new interesting mechanics.

The meta-progression through an NG+ cycle, ammo / max HP upgrades, unique end-game fit weapon loadouts through Bloody Shotguns, definitely fit for a modern game design, it's somewhat similar to what Doom Eternal did.

It's also an interesting name considering the expansion is developed by MachineGames. "Quake: Dawn of the Machine" as in dawn of new MachineGames Quake era.

It's especially weird that the new episode is completely free. Why would Microsoft allow MachineGames to work on free episode for so long if not to prototype and advertise the IP for a future purpose?

i want to sniff the copium too

It’s a nice idea, and I would tentatively like this to be the case, but I don’t think it is. In the same way the doom reboot is a very different game to the originals (for better, worse, or both), a new Quake would leave us fans returning to the original. DOTM is the best thing that they could have ever given us, it really will never get better than this - unless they produce another episode every 10 years. I for one would be happy with that, I don’t feel the need for a new Quake that ultimately would be a compromise, for a new audience.

Machine games have a quake club where they make maps together for fun, so in down time I assume they put this together. I don't think it's a sign of a quake game... but stranger things have happened...

A few people of the studio created this in their free time. So there's nothing to hypothesise. I do wonder if they got paid, or the studio got paid, for releasing it. I think it would generate a bunch of new sales.

I do hope that quake club will do another Quake 2 episode with this quality as well, that game doesn't get enough love.