Dragon Quest XI S is a lock for Japanese release in 2019. There's no doubt about that. The good news is, a report states that both North America and Europe will get the game this year as well.
While nothing has been officially stated by Square-Enix at this time, multiple sources in the supply chain are showing that Dragon Quest XI S is going to launch in both NA/EU in 2019 as well. It certainly seems plausible, and hopefully Square-Enix confirms this news in the near future.