Rebble effectively had free reign on this ecosystem for years, and could have at any time decided to try and capitalize on it further. They still can! But instead they're apparently interested in rent seeking while Core makes real headway.
It's clear that Eric and Core want to make something now. It's not clear what Rebble wants, but it's clear they are feeling left out. That obviously sucks but it's clear from what both sides are saying that Core has been trying to involve Rebble in their efforts. That's certainly noble and I'm not sure others would do the same.
Would Eric be able to do this all without Rebble? Lots of commenters have been saying "no" but I'm skeptic. I was an early Pebble user. I stopped using it before they went bust, and while I was aware of Rebble, there was nothing compelling there for me. It's neat that they have maintained a copy of the original watchfaces but beyond that I don't perceive a ton of value. I don't like the subscription fee. I'm sad they never took a serious crack at making a Rebble watch.
I hope everyone finds a way forward, together, but I'm not optimistic.