To me the follow up questions matter when deciding this. If it’s included in the core for convenience and the NodeTypes package isn’t adopted, then I wouldn’t want it in the core. However if the core packages are adopted to the standard, then it might make sense IMO.
Atomic.Fusion is a opinionated and little more complex (learning curve) compared to how it is in the core currently as I see it. Although it’s definitely a good default, I see it as one of many ways to do things. When I look at the package, it’s about adopting that specific style of using Neos, something I’d be reluctant to personally.
On the other hand I have no problem adopting the package an approach supported by the Neos team and making it an official Neos package, but optional.
I was actually looking for an option to include AFX into the core instead of Atomic.Fusion as I see that as a more generic useful thing and not opinionated the same way but more a generic building block.