I don't know how credible is this Reddit insider, but that sounds more like fantasy booking more than anything.
The WWE has done the "forgive and forget" in the past, so it's not entirely feasible that Ambrose and Rollins can team up. Especially if they have a common goal, which in this case, to take out Reigns and his stable. Rollins can come back and claim he never lost his title, and that he's gunning for Reigns, which will automatically make him a babyface. (I'm probably in the minority, and actually prefer him as a heel, when he returns).
However, it would make no sense for Gallows and Anderson to align themselves with Reigns and The Usos, when literally weeks ago, they brutally attack them. I know the WWE thinks their fans have terrible memory, but that's just pushing it. Besides, it looks like Gallows and Anderson are going into a feud with the Usos, anyway. So why on earth would they be in a stable together, after feuding with each other?