The domains www.pokemonletsgopikachu.com and www.pokemonletsgoeevee.com have both been registered by CSC Corporate Domains, the same company that registered the official domains for Pokemon.com, Pokemon Sun and Moon, and other Nintendo titles. In instances like this, the domains always have dummy registrant information until the games are revealed.
This still isn’t “smoking gun” proof of yesterday’s Pokemon Let’s Go! Pikachu and Pokemon Let’s Go! Eevee rumors, as over the years Pokemon has registered domains for game titles that fans predicted could be made, such as Pokemon Gray and Pokemon Aqua Blue.
Sun and Moon were announced the day after their domain was registered, so we may get an announcement tomorrow. However, it’s very likely yesterday’s rumors, if real, spurred Nintendo to register the domains earlier than they intended. So the announcement may come later.