Katakuri is ripe to come back, post-WCI his character was really opened up to the world. Not only did he find someone to acknowledge his disfiguration, he himself acknowledged and embraced who he was. And then, of his own god damn accord, fell on his back. Voluntarily losing the fight.
With his old self gone, Katakuri's opened up room to grow, as a person and a fighter. And considering the state of affairs, rn it makes a lot of sense for Katakuri to be involved in the plot.
His entire ambition is protecting his family no matter what and now that Linlin is MIA, he's the unofficial leader, like the BMPs hinted at when they arrived at Wano. And on his watch, Germa attacks his siblings, Kuzan freezes Cracker and kidnaps Pudding, so he has all the drive that's needed to step up and reenter the plot.
Law is a little more likely, he never got the "dropped out of the PK race", but I'd find it redundant if Law got beat by them and immediately returned to help kick their asses. I think Katakuri's return is very likely