Nintendo's plans for 2020 remain veiled in secrecy. While more and more third-party games are being ported to the Nintendo Switch, relatively few first-party games are slated for the year. Beyond Pokemon Mystery Dungeon: Rescue Team DX and Animal Crossing: New Horizons in March, Nintendo's 2020 schedule is open. A new leak may have revealed some of Nintendo's plans, however, hinting that both Paper Mario and 2D Metroid may be returning in 2020.
Reliable rumormonger Sabi revealed some new information that they'd received from various anonymous sources on Twitter over the past 24 hours. After having "looked into it for a bit," Sabi said they felt confident enough in their sources to confirm both a Paper Mario game and a Metroid title for 2020. According to their information, Paper Mario 2020 will be "going back to how it was," and the 2D Metroid game seems "to be related to Fusion."
The most recent releases in each franchise weren't too far past. Paper Mario had Paper Mario: Color Splash for the Wii U in 2016. It was perhaps the Wii U's best game of the year, but it wasn't a year that the Wii U had much success in general. Metroid: Samus Returns, a remake of Metroid 2 for the 3DS, was released in 2017 and was very well-received. Both franchises are well-regarded and feature few if any missteps. It would make sense for Nintendo to revisit them as it makes sense.
While Sabi doesn't have any further information to share yet, it's interesting to speculate about what she did say. Paper Mario "going back" could mean the series will return to its RPG roots and will be akin to the original game and The Thousand-Year Door. A 2D Metroid related to Fusion could mean that the 2002 GameBoy Advance title is the next to get a remake, though it could be a sequel as well.
For the time being, Sabi's leaks are unverifiable. As such, they should be considered rumors until further evidence is provided or an official announcement is made. Sabi is a reliable rumormonger most of the time and has leaked several other Nintendo announcements. That said, not every one of their leaks works out. For example, Sabi previously revealed plans for the Metroid Prime Trilogy to be rereleased, but has since said its been delayed. It'd be awesome if both Paper Mario and 2D Metroid return in 2020, but things don't always work out.
Expect more information on Paper Mario and 2D Metroid for Nintendo Switch in the months to come.