I think Paper Mario has a future but I have been wondering something similar based on whatever Intelligent Systems are up to. After Origami King, they've worked on Fire Emblem Engage and two WarioWare titles (though Get It Together! was mostly finished around September 2020). If various rumours pan out, there's also a Fire Emblem 4 remake in the works and a Paper Mario remaster. The former doesn't surprise me and I suspect it may be the work of the Three Houses team, more or less (IntSys with Koei-Tecmo heavily involved).
The fact there's supposedly a Paper Mario remaster coming has always interested me. The usual schedule for Paper Mario would mean the next title is more or less due in 2024, which is currently the launch year for the Princess Peach game. Super Mario RPG remake rules out Paper Mario appearing this year, if the remaster is real. Potentially a Paper Mario remaster and the new Princess Peach game both end up launching in 2024. So I have been wondering if Princess Peach is an EPD x Intelligent Systems joint, with the Paper Mario brains heavily involved, with Paper Mario temporarily on the back burner (but still important enough to Nintendo that they want to keep the series regular presence through a remastered release). The obvious caveat there is that, as of yet, we've no idea if the Paper Mario remaster is actually real, nor do we know if it would be a full price release or a Pikmin style port built on the Hagi emulator.
I don't think there's any solid plans for Nintendo to continue Super Mario RPG and Princess Peach as 'replacements' for Paper Mario, though. The big question mark really is around the actual developers for Mario RPG and the Peach game. In both cases, we've no idea who is actually responsible for the games, and that in turn means we've no idea if those development arrangements are actually sustainable in the medium or long term. It's not unprecedented to see Nintendo's franchise offerings evolve, though; we've just seen the Bros sub-series in Super Mario go a decade without a new title (albeit with a port in 2019) while Nintendo experimented with Maker titles on Wii U, 3DS and Switch.