For now, Nintendo is remaining frustratingly vague on that key question. In an investor Q&A (partially translated by Twitter user Cheesemeister), Nintendo President Shuntaro Furukawa said that "while our company is always considering various specs for future hardware, I will refrain from making specific comments about future hardware here... Our company wants to continue offering unique ways to play with its integrated hardware and software business, so please look forward to it."
It's hard to read too much into that non-answer, considering that Nintendo hasn't formally announced any details about its next console hardware yet. Later in that same Q&A, though, Furukawa noted that "as for the transition from Nintendo Switch to the next-generation machine, we want to do as much as possible in order to smoothly transition our customers, while utilizing the Nintendo Account."
That's not completely new information; Nintendo said in a 2020 investor presentation slide that it planned to use the Nintendo Account for its "Integrated Hardware-Software Next gaming system" releasing in "20XX." Still, a new quote stressing a "smooth transition" and a legacy account management system could be seen as a hint that Nintendo plans to let Switch players bring their game libraries forward to new hardware.
Nintendo has a long history of backward compatibility on its portable systems, each one of which could play games from the previous generation in a chain running from the original Game Boy to the Nintendo 3DS line. More recently, the company implemented a similar chain of backward compatibility from the Gamecube through the Wii U, the latter of which could even play downloadable games transferred over from the Wii.
But Nintendo broke its chain of backward compatibility with the Switch, which merged both of Nintendo's hardware lines into a new "hybrid" platform. Meanwhile, Microsoft and Sony were increasingly focused on backward compatibility as a marketable feature on their latest Xbox and PlayStation consoles.
From a game development standpoint, Nintendo's Shigeru Miyamoto noted in November 2022 that in the past, software development environments "could not be brought forward when the hardware changed, and it would become impossible to play software released for previous hardware without making changes." More recently, though, the integration of those development environments across hardware has meant that "generally speaking, it has become easier to implement an environment where software released for past hardware can be played on new hardware," Miyamoto said.