Nice, so most likely 2018. game.

Great news! Pikimin 3 is one of my favourite WiiU games.

might as well put it on the backburner until the install base grows

with less third party than the competition, Nintendo can put some exclusives in quieter periods which should help them sell a bit better, and Pikmin 4 would be a great release in that kind of period

The other 4 games I can see being 2018 for sure. Pokemon, though... no.
If they have just begun development for a Core Pokemon RPG on the Switch, I would not expect it until 2019 or 2020 because of 2 reasons:
1. That's usually the length that fits between each generation
Red/Blue (1996) - 3 years-> Gold/Silver (1999)
Gold/Silver (1999) - 3 years-> Ruby/Sapphire (2002)
Ruby/Sapphire (2002) - 4 years-> Diamond/Pearl (2006)
Diamond/Pearl (2006) - 4 years-> Black/White (2010)
Black/White (2010) - 3 years-> X/Y (2013)
X/Y (2013) - 3 years-> Sun/Moon (2016)
Sun/Moon (2016) - 3-4 years-> ?/? (2019/2020)

2. I wouldn't be surprised if it's even longer than 4 years considering on how this will be the first HD game in the series, BY FAR the biggest project Game Freak has ever done.

Glad they haven't forgotten about it. I was beginning to wonder.

I was hoping we would see Pikmin 4 this year at E3, but considering they announced two Metroid titles in development, one actually coming this year, so can't claim to be that disappointed...
Given how long we were told Pikmin 3 was in development, clearly Miyamoto isn't afraid to show these series a little extra love and care before sharing it with the world...
Now that I think about it, I'm kind of surprised Pikmin 3 isn't getting a Switch Port...

So Pikmin 4 for the Switch 2 confirmed? I am getting Pikmin 3 E3 2009 flashbacks.

Basically completed...

..two years ago :/

Miyamoto December 2014 - "No worries about Starfox, Starfox [zero] will arrive before the Legend of Zelda next year."

Miyamoto July 2015 - "Pikmin 4 is in development and "very close to completion"

T_T

Pikmin is not a high priority project for Nintendo. The series doesn't sell well and is very niche in appeal. If it wasn't for Miyamoto they probably would've let Pikmin died already.