USUM should have been a DLC, it didn't bring nearly enough to be it's own game and be worth another 60$(AUD) and you could argue that things like Necrozma's story and Mantine Surfing *should* have been part of the Base Game. And personally I'd actually purchase an additional story DLC while I absolutely refuse to use my money on slightly dolled up copy of a game I already have.
Only because EA uses that concept less than optimally doesn't mean GF will do that as well, EA is pretty bad about a lot of things. Ads for "micro transactions". Eh, micro transactions aren't the same as DLC, and even if micro transactions show up in Pokemon it's probably for crap like "Ash's Hat" or "Cyntthia's hairstyle" stuff nobody really needs and that is very easy not to purchase without missing anything.
For a positive example of DLC look at Ubisoft's "Southpark; Fractured but Whole" the basegame was a complete experience and in March they released a story DLC that added a short side-campaign. It made me dig out the game and play the whole thing again. And in Summer there will be another similar Story DLC. There are some cosmetic DLCs, but well....who needs those?
I mean it's the difference bewtween playing 60$ for a (very slightly) enhanced version of something you already own or, let's say 20$ for the new stuff from USUM to be added to regular SuMo.