Anything downloaded from the Switch e-shop will continue to work locally on that Switch, and all the mainstream games can be bought as a cartridge if desired. It's not fundamentally different than dragging out my old N64 to play my old games from the 90s. I don't consider that "renting", and I can't remember the last time I had the desire to play one of my decade+ old games anyway. Very few of them aged well compared to their modern versions.

I'm sure there are some people out there that are passionate about this but I can't imagine it being anything more than a small minority of video game buyers. There are certainly other ways the Steam Deck could be disruptive though.