I think they would provide a fairly varied and interesting unit list, on the ground we might see Nikto soldiers, Hutts (Though rarely), skiffs, sail barges, IG droids, mercenaries/bounty hunters, Gamorreans, etc... There would be a lot of exotic and weak, but usually cheap, units for them.
In space, in addition to ships that you have already listed, they could use any Zann ships as the Consortium, neighboring Hutt space, has broken down in this time frame and their assets have likely been acquired by the Hutts, plus requisitioned ships, like the Crimson Jack style battlecruiser that Jabba refurbished for CJ and then later recovered after Solo defeated the pirate. Old pirate ships such as Z-95s and Y-Wings, and some of the stuff coming out in Fantasy Flight's line of X-Wing ships could be useful. Also, I know most of Rebels is off the board, but the merchant TIEs shown in one of their episodes could make for an interesting variant in the service of the Hutts. And since they feature a lot of ugly, refurbished, vessels, Corey could always give them those Nar-Shadda SDs he thinks are so ugly.
I wouldn't mind if they were playable or not, but, if playable, they should start out fairly weak after everything they have gone through in the past two decades, losing Tatooine and Jabba, battles with the Seperatists, Darth Maul's Shadow Collective and the Zann Consortium, plus fighting Maldrood in ICW's timeframe. It is a testament to the Hutts power that they have held onto their core territories after everything.
