You hit the nail on the head.Having not seen it yet (this is my Friday, so will see it this week), but from the previews it seems more focused on the X-23 storyline, just set in the Old Man Logan time frame. I could be totally wrong about that of course having not seen it, but that's the impression the previews leave me.
K krichardson the creator of Spawn, Todd McFarlane, has been talking about a another movie for like 10 years. Supposedly there is a script now so maybe we will see something in the next couple years.