I would love a portable that fits in my pocket again. I know people argue the Switch is pocketable, but it comes with a bunch of compromises. Sure it can fit in a pocket, but it isn’t comfortable. Plus the screen is exposed makes me hesitant to put it in there (Give us GameBoy Micro style faceplates, and I’m fine with the exposed screen). The worst part though is the vents on the system. Those are begging to eat lint up. A potential Switch Micro would need to address all of these. It might need a significantly more power efficient chip, which would reduce batter size constraints, and allow it to run cooler, removing the need for a fan and vents.
Historically, Nintendo has announced things with that kind of lead time, but as of late, Nintendo has kept announcements much closer to the launch date. The Switch from announcement to launch ( Oct 20-March 3) is 134 days. Today, January 11th, we are 137 days away from Memorial Day (May 27), which is the unofficial start to Summer. The real start, June 21st, is a month after that.
My point is, things are way more open. Nintendo can announce and release the thing very quickly if they want to, and I find that much more likely than the drawn out reveals over 18 months that the Wii and Wii U got.