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It's "2018 or later." It has a good chance of coming out next year.
Most likely scenario, in my opinion, is that Gen VIII comes out on Switch next year, then a gap year as GameFreak works on a third version and/or Sinnoh remakes.
That way, Switch gets a Pokemon game ASAP, GameFreak makes some of that sweet console money, and gets better adapted to the system. Not to mention it's very likely they've been working on it for a long time now.
