As sad as this news makes me for the preservation of eShop stuff, the modding community tends to rally around Nintendo products and I have pretty high faith that things will be preserved one way or another by the awesome work of modders and the emulation community.
It's a sad state of affairs for copyright law, but generally by the time Nintendo shuts down "official" access to content for a console generation, rom files are readily available from a few google searches and a relatively well-thought-out and simple modding process for the hardware.
There are many first party nintendo games and remakes that still haven't made it to newer consoles like the Switch yet. Hopefully Nintendo comes up with better backwards compatibility in the future for current Switch titles, but assuming they won't as they often don't, piracy and emulation tend to fill in the gaps pretty well in my experience.
It's a sad state of affairs for copyright law, but generally by the time Nintendo shuts down "official" access to content for a console generation, rom files are readily available from a few google searches and a relatively well-thought-out and simple modding process for the hardware.
There are many first party nintendo games and remakes that still haven't made it to newer consoles like the Switch yet. Hopefully Nintendo comes up with better backwards compatibility in the future for current Switch titles, but assuming they won't as they often don't, piracy and emulation tend to fill in the gaps pretty well in my experience.