I'm not totally sure if Disney will do this, but I'd really like to see a single, side, film. Something that's really dark and gritty, focusing on smugglers or bounty hunters (I'd also like to see a Fett movie like havires mentions, esp. since the Jango Fett game was pretty good, iirc). As long as they don't make it about Han Solo, and instead focus on some young gun who doesn't really know what he's doing at first, I think it'd be great.
True they probably would, but there is nothing saying they couldn't go back to Han's early days and make the movie about a young Han that has no idea what he's doing. If that's where they want to go. Although I would probably like it better to focus on new people in the stand alones with cameos from the names.
I mean I'll be honest if they do an origin on Han, since RoTS was 20 years or do prior to New Hope, they could start it right after that battle on the Wookie planet where Chewie is shown with Yoda. Like after the battle Chewie leaves his world on a smuggler ship, which we find out after the iconic title scroll is the Millennium Falcon. With Fett (coming in a bit later) as the bad guy. Then again that's a different idea to be honest.