Yep. I plan on making my own 5e clone using the CC mechanics pretty much verbatim. I kinda hope they put the updated rules kernal for ODD in the CC as well, though I doubt it. I have a feeling the skill rules especially are going to be more what i want than the current 5e mechanics. But I built a whole system that rides almost entirely on it's 36
No one said "everything under the 5e rules". Even the OGL doesn't grant that. The CC proposal makes it possible to copy-paste the core mechanics of 5e in specific without any possibility to a copyright claim for using their expression of the ideas contained therein. This is all the bulk of the original OGL does, barring things like allowing the free use of certain named elements that are pretty clearly copyrightable as specific expressions of ideas. But a game using that core rules kernel is compatible with 5e dnd, and never has to worry about a copyright claim based on that similarity.
It's not that KP could just continue all the same products, it's that they can easily just keep doing what they have been doing, creating new stuff that builds on that ruleset, just being more distanced with the creative work side of it to keep it non-deriviitve. So, no new Ghoul Empire products, unless they don't actually reference the specific idiosyncratic features of 5e dnd ghouls, and instead just use KP worldbuilding material and brand new mechanical options. Not only that, they could put out a new game product that just presents original classes based on broad fantasy archetypes that aren't the same as those in the dnd PHB.
They could probably even put out fighter subclasses, by just not explicitly naming the fighter, but that would be awkward, and at that point they'd be better of using the OGL just in terms of product clarity.