Once again I'm going to say the same thing I've been saying for maybe 6 months now. Concerned Nintendo fans here are just overthinking it because your perspective is tainted. There is no conspiracy or complicated mystery here. They developed two games in parallel for two very different platforms. They announced a commitment to support a third platform as well to cover all the bases they need to in Japan. That's all. It's business. With the development of the game taking longer than expected, it is obvious they would want to focus on the main platforms and release those first. Are there likely other deals with first parties with regards to marketing and so on? Absolutely. But that's how every big publisher these days operates.
DQXI Switch is not ready to be shown. DQXI Switch will most likely be a port of the PS4 version with maybe some extra bells and whistles to make up for lower technical specs. It will come out later and it will be full price. I think we can reasonably expect all that. There is no immediate rush for S-E to start marketing it before they even release the game on other platforms. The Switch userbase will only increase with time. If the game is good, word of mouth will make people who don't already have it more willing to buy it on a brand new platform that's popular. Even if word of mouth is lukewarm, it's still DQ.
As for the "omg protect people from spoilers" thing people keep throwing around to insist that the Switch version has to be close... well... lol no one really cares. It's just something Horii says. He's not even the producer of the game. Business and development realities change what Horii can "want". Remember that Horii also wanted DQIX to be somewhat realtime action based. He also once said that DQ will always be only on the platform which sells the most in a market. He also willing works with a far right war crime denier.
Okay maybe the last part isn't relevant.