Very good discussion here, so I figured that I'd drop my two cents in.
Right now, the only thing I fully expect gameplay wise for the next Tamagotchi to keep the 4U screen size and NFC, but to also include more raisable characters and bring the teen growth stage back - in fact, I'm expecting close to (If not the same amount as) the number of characters featured on the iD L and P's to be built in, but I don't see them surpassing the iD L's grand total of 48 characters (4 babies, 6 toddlers, 6 teens, 32 adults) just yet. It should be noted that the main reason that most people didn't enjoy the 4U and 4U+ so much as compared to those (Myself included in this group) is because of the lack of built in characters and the EXTREME reliance on the Touch Spots and the Android app... and because the latter requires very specific NFC hardware to work with the 4U properly, we all know how that turned out. With this year being the 20th Anniversary, I highly expect at least a few vintage characters who we haven't seen in a while (Ginjirotchi, vintage Masktchi, Nyorotchi, and Tarakotchi being the most likely for obvious reasons) to be part of the built-in raisable lineup. I don't expect a fan vote like they did for the 15th anniversary though, considering that we're due for a new version to begin with.
This year is also the 15th, 20th, or 30th anniversary for a lot of Nintendo IPs. If Nintendo and Tamagotchi were to collaborate in some way, I would love that. But again, I don't know if Pokemon would be seen as an obstacle since it's Nintendo-exclusive. They may feel like they have loyalty to Gamefreak or The Pokemon Company
Although Bandai did make the latest Super Smash Bros. game... it's complicated.
As you said, I highly doubt they'll do something with Pokemon because Digimon (Unless of course there are plans involving them that they're keeping their mouths shut about for now - next year is Digimon's 20th anniversary, after all)... but any other Nintendo franchise can and likely will get something for the Tamagotchi 20th. Super Mario Bros being the most likely for two reasons...
#1 - Mametchi appeared in Mario Kart Arcade GP 2 as a playable character, and said game also had several Tamagotchi themed items.
#2 - Minna de Tamagotchi World 64 featuring Mariotchi and Waruotokotchi (The latter of whom is based on Wario). Enough said there.
So yeah, I won't be surprised if Mariotchi or Sonictchi from Sega Saturn de Hakken! Tamagotchi Park (The latter also being a posibility considering that this year is Sonic's 25th anniversary) make their return as some kind of Touch Spot or DLC. As for other potential cross promotions? Due to Bandai Namco owning the rights to the series I'm about to mention, I also see characters from Kamen Rider, Super Sentai (Power Rangers), and The IDOLM@STER (Which are celebrating their 45th, 40th, and 10th anniversaries respectively this year just as Tamagotchi is hitting the big 20th) being highly possible as getting "Gotchi-fied" to become raisable characters via the same means (Touch Spot / DLC).
Due to the mecha (Zords) in Zyuohger (This year's Super Sentai series) having pixel inspired designs, it's very likely that we'll at least get the Red Ranger's Cube Eagle as a raisable character - in fact, I've already stated my theory that Tamagotchi's 20th anniversary has something to do with those designs over at Rangerboard. As for Kamen Rider and IM@S, the likely candidates are definitely Yurusen (Mascot type character from Kamen Rider Ghost) and Harukasan (Puchidol version of IM@S's main character Haruka Amami) respectively. Anything else we get for cross promotional material would be the cherry on top of an already awesome cake, anniversary year for involved franchise or not.
TLDR... expect BIG surprises for the next Japanese release. I know that I am. Oh, and Linktchi and / or Samustchi please (Zelda and Metroid hitting their 30th this year). K THX BAI!
