For imperials/first order: special forces tie as a small turret. First order shuttle (kylo rens shuttle) as a large probably non turret ship. Maybe the new troop landers though I think that's unlikley.
For rebels/resistance: maybe the new falcon, probably another rebel fighter. I doubt the movie will only have t70s and I recall a bunch of leaked concept art for other rebel fighters ages ago.
For scum: well the current pattern has been bounty hunter ships and ships from Star Wars galaxies so they could continue with that, but they are out of famous bounty hunter ships except maybe the slave-II. I think a good (and canon!) direction scum could take is ships from the clone wars. No I don't mean arc-170s or v-wings or anything. I think th chances of seeing those ships in x-wing are slim to none and really wouldn't feel appropriate in scum.
But the clone wars series does have a lot of cool unique and thematic ships used by criminals bounty hunters and hutts that could be used without people getting all upset about 'prequels stuff.
Some examples:
Small ships
http://starwars.wikia.com/wiki/HH-87_Starhopper
Small hurt cartel fighter that actually just appeared in the recent aftermath book.
http://starwars.wikia.com/wiki/SS-54_assault_ship
http://starwars.wikia.com/wiki/Rogue-class_starfighter
Large base ships
http://starwars.wikia.com/wiki/Sarisa-class_gunship
http://starwars.wikia.com/wiki/Aurore-class_freighter
http://starwars.wikia.com/wiki/Kom'rk-class_fighter/transport



