I do think normal Sinnoh remakes are coming out next year, but even if Let's Go Johto isn't a thing, I still think paired Crystal remakes are releasing before the eventual Unova remakes.
Way I see it, since FRLG came out after RS, the next region that we were due after ORAS was Kanto. Since RG had already been remade, they opted for Yellow. So we'll get DP remakes and then either this generation or next, a Crystal remake. But if they've decided not to continue the Let's Go series (either because of critical backlash or because LG was very specifically about Gen 1 nostalgia), they'll still remake Crystal rather than skipping it, they'll just do something different with it.
Of course it could be that Let's Go Johto does happen, just not till Gen 9. Either way, I think the remake order will be Sinnoh-Johto-Unova.