From a mechanics point of view, I actually think what Scum needs is support ships. Sometching cheap to carry the like of Jabba would be nice or something with a wacky skill set akin to the Quadjumper. While I don't think Scum have to have a four dice primary, it could certainly use it. While I would prefer something more agile myself, the Gauntlet Fighter could be interpreted to be the heavy duty, 4 att ship.
From more of a personal point of view, including more independent cultures (like the Hapes Consortium and more Mandalorians) would be nice to see. As well as groups like Talon Karrde's Smuggling Allience would be fun to have references to.
As for what is next, it is most likely a Scum version of the Falcon.