It’s only limited if they stay obsessed with Clan Skywalker. There’s tons of room for plot development if they get back to the original blueprint. The Expanded Universe (ie all that stuff that was canon until Disney bought SW and made it all not canon while bringing some stuff in) was HUNDREDS of books, and comics, and video games. The vast majority of which never had a Skywalker, and even the stuff that did they were usually minor characters doing cameo appearances.
Who cares if Snoke was undeveloped. It’s not like we knew anything about Palpatine when Vader threw him down the pit. Really we probably know more about Snoke now than we did about Palpatine when Return ended. As for where can it go: there’s a new Emperor in town, and a rebellion, and a bunch of characters and a huge galaxy.
So the rebellion is almost smashed. There wasn’t much rebellion left after Empire either. The one thing this rebellion has though is seeds. I see it going kind of Hunger Games, there’s going to be a lot of rebelling that isn’t actually tied to the rebellion. The big question is do they kill Ren or reform him.
I don’t really worry about the names. I’m hoping they drop way back. Old Republic or Pre-Old Republic. There’s good stuff in that section of the story, and a chance to really cut away from Clan Skywalker. We really need a trilogy with no Skywalkers, they’re what limit the story.