Parallels are drawn between Scalebound and Astral Chain as both were character action games (even if we didn't see a lot in the former), wherein the player has a secondary AI controlled companion fighting alongside them, of which can be integrated into existing combos or tasked with autonomous offense and defense functions with item support. On paper, from the little we know about both, Astral Chain has all of these functions also. In the latter you can command your Legion to fight independently, and support them with items.
It might seem superficial, but it's probably a hold over of ideas from Scalebound, largely reinvisioned but still fundamentally based on the Player Character + AI Partner concept, namely Platinum's take on that AI partner and how they integrate with combos and operate individually.
The biggest change is scale (pun intended), as Scalebound seemed much more like Kamiya's vision of this idea however the size difference between each character being far vaster. A game where you partnered with a semi-autonomous AI, but the scale of battles ranged much larger.