Anyways, lemme explain some stuff about Sans in Revenge Reimagined in short:

Except ACT 1, he doesn't play a major role other than representing the amount of Genocide we commited.

As Mike said, he would fill a supportive role for Papyrus in ACT 1, he'd be like "maybe it's too late for me, but you can still save yourself bro."

He's going to appear in ACT 1 and probably ACT 4

By the way, if you're gonna question why is the slash grey, it is not his wound, it's the deathmark.

It's a reference of Madness Combat... you know, people got send into Purgatory after they died and have the deathmark things sjjdjsjjxjsjfjjdjdn discover it yourself