Yea, I think they will all fight again, but if you mean not at the level we are used to in Pacs case, or that some expected them to reach in Quillins, I think that's fair.
Manny could still well beat anyone at 147 not named Floyd, he could lose to a few as well of course and I highly doubt he will take on someone like Thurman or Brook.

Quillin doesn't have the craft to be an elite guy, but he can punch and still has time and options to build himself back up. He has no chance against GGG imo, but could still get in the mix, maybe even be CAneos first opponent at 160 if he doesn't want the Kazakh either.

Kirkland should retire though, no doubt.