Federal, well the conglomerate that owns Federal, Speer, Sierra, CCI and others bought the ammo part. I don't think they have any plans to use the same facilities Remington used but only to make it where their other ammo brands are made. So dunno about all that excess capacity. I think all of them are wide open now.
The Remington firearms part was also bought up but not by a gun maker. I can't remember right now who it was, maybe Palmetto but am not sure on that. I keep seeing ads on TV making me think maybe long guns at least are returning, I'm just not sure.
I don't think anyone has any plans to use the Huntsville, AL facility where Remington was making most all their firearms toward the end. That's a shame, lots of already trained folks and a huge facility and equipment.
I think CDNN must have bought most all rifle and maybe shotgun parts on hand so whoever wants to make rifles will have to start from scratch.
Ruger says they will make the Marlin 1894, 336 and 1895 and maybe the semiauto 22LR which I think is a Model 99. I've not seen any mention yet of others. About the only Marlin I'd be interested in these days is the bolt action tube magazine .22 magnum and maybe an 1894 or two depending on price. The tube fed .22 mag tho I'd sure buy if I could find one.
Of course I've been saying that about a Weatherby Mark XXII with tube magazine for years and now I've found one and am passing on it at $785 plus shipping and price for local FFL to accept it for me. I just don't want it quite that bad.