I don't think any of the rumors are about a new console to replace switch. Just a Switch Pro akin to what the PS4 Pro and Xbox One X were. Totally optional for people who want to play the same games with higher resolution, higher frame rates etc.I dont understand this need that Nintendo have to make a new Switch now. They don't. The Vita came out in 2011 and was the better handheld on paper and Nintendo never really saw the need to drastically improve their handheld until Switch. They have a nice spot where they are either the only gaming platform people own or they are the complement to gamers system of choice (Xbox/PS/PC). They released an underpowered home console in 2017 and it is selling gangbusters. There is no rush to enter the power market with a possibility of backfiring like Gamecube.
That would be a money maker for them as it would get some people to upgrade and they always sell their hardware at a profit from day one. Hell, I have a launch Switch and as Switch Light and I'd probably upgrade to get 4K upscaling and better frame rates in games like BOTW, Hyrule Warriors Age of Calamity etc.