And in 2020 it is totally clear that Pikmin 4 was not close to completion because otherwise it would have been released by now.
Like I said, Nintendo never put Pikmin 4 on their release lists in financial statements. Other games that were announced early, like Metroid Prime 4 and Bayonetta 3 can be found on those lists, but Pikmin 4 never showed up. That is especially weird if you believe in the link you posted, that the game was not only in development, but already close to completion.
Furthermore, Miyamoto said that "the Pikmin team is always working on the next game" which is laughable considering the sales of the IP.
Yeah, I figured that they had it pretty far along for Wii U and then when they transitioned to Switch, the team mostly got put on different projects.
Still, real weird either way. Nintendo said clearly Pikmin 4 is in development so maybe its just vaporware at this point. I'm taking that as an official announcement though.