There's also a strong possibility star is being removed in DT (and Assize) given how they are absent in the job trailer, and one of the new-looking skills for AST (the final one shown) has the same animation as popping a star. Thematically it looks like a replacement to star too.

Given the state of healer toolkits, just giving them more healing buttons is silly but if they removed some of them (sigh) then it would technically make healing harder, and something like the Lady card more useful if you're losing star.

If it is removed or replaced by something else, it'll most likely be something that is simply less interesting or nuanced to use. Star was used every minute for its damage, but you could've still placed it where you want for its healing. Like in P10S where the DPS light party go east and the supports go west. You were too far to heal the DPS who took damage from the mechanic (forgot name), so placing a star allowed you too still do damage but heal players outside of your casting range.

I guarantee whatever is replacing it will probably just be an OGCD healing tool with less nuance, which is just another notch of stripping away the difficulty and complexity of AST's tool kit.