Five locations revealed, counting Jakku; which as already stated features two maps. I'd say there's a high chance that each planet will feature more than one map; possibly a mixture of small/medium/large.
Lack of singleplayer isn't really an issue. Battlefield games have had notoriously poor singleplayer (although Bad Company was amusing, and Hardline played like NCIS/Hawaii Five-0 on LSD). Co-operative missions could be interesting, but as Deadfire already said this is more of a reboot than a continuation; if there's a sequel down the line then it'll come along then.
That said, I could have gone for a campaign circulating around the New Republic's campaign against the Imperial Remnant post-Endor. I doubt Jakku was the only battle fought.
Space battles, eh, it isn't a huge loss. It'll either make it in as DLC/into a sequel, possibly as a twist on Carrier/Titan Assault. I wasn't overly fond of them adding space in Battlefront 2 anyhow; I much preferred the aerial battles in the first game. Although I still have nightmares of X-Wings crashing into the platforms on Bespin.
Gameplay trailer now coming today (tomorrow for the colonials, damn timezones). Curious to see what changes have been made to character customisation outside of the weaponry/equipment.