Trademark registrations have been apparently found, as well as logos, for two unannounced games: Pokémon Sun and Pokémon Moon! These were filed one day before the Pokémon Direct and beginning of the 20th anniversary in Japan.
UPD1: Numerous Pokémon Sun and Pokémon Moon websites have been registered by different subsidiaries of Nintendo. All of them direct back to Pokemon.com. Looks like we know what our next games are, maybe.