I think you're stretching your point too far if you think Grey Goo was just a SC clone... Grey Goo is clearly in the the C&C branch of RTS more than the StarCraft branch, and of course made by Petroglyph. It's macro-heavy base-building, not micro-heavy, even as the Goo, it doesn't play the same as SC at all. It's also more than a few years old now (10)... On release the focus was the campaign, it didn't even release with replay or observer mode for multiplayer.

Tempest Rising is a newer RTS (this year) that's also in the C&C style, its highlight is the campaign. (Multiplayer I think is basically in the go-to-discord phase already.) The real problem is that RTS is just an unpopular genre, whether it's taking design inspiration from the C&C branch or the SC branch.