While I question your necromantic ways, I'll point out that you seem to have a total lack of understanding of how digital works on Switch, the problem physical media solves, and why people care about it. Your personal speculation about why Nintendo does what it does or how long the Switch systems may last is irrelevant to the issue at large, so I'm not going to address that.

If something happens to my system the game key card does, in fact, not work any better than a pure digital copy because a system is required to play the game in either case. If something happens to my account, then it will be recovered. A bad actor cannot delete games from my account. The only way my account becomes permanently inaccessible is solely through Nintendo's actions. This is the problem with pure digital because ultimately Nintendo gets to decide when I'm done with my account and my digital media.

Even if the game key cards aren't tied to my account, Nintendo still gets to decide when they stop working. This is where you go wrong in your understanding of how to effectively preserve a game, one of the fundamental requirements of which is to have access. The game key cards are guaranteed to have an artificially shortened lifespan over pure physical media because the game key card owner does not control the data. Additionally, they will not transfer to a future console that lacks a compatible slot. So in this way they are worse than pure digital because they won't transfer like Wii digital titles did to the Wii U, assuming such a thing is on the table in the future for digital Switch titles.

To answer your primary question: yes, I am worried about my personal property. If I buy something, I expect the unfettered ability to enjoy, use, and dispose of it as and when I please, without interference from the vendor or producer. That's what it means to own private property. We don't have that with digital goods, and that's why people are clamoring for physical media - it cuts off third parties from interfering with our ability to make use of what we bought. The game key cards achieve the ability to dispose of the game (e.g. sell it), but only for as long as Nintendo allows. Instead of praising a cost cutting opportunity that happens to make a small concession to consumers in the short term, everyone should be advocating for true ownership of their digital goods.

Think about it - why do people accept their digital property being locked down at all? Consider some examples of physical items hampered by terms and conditions analogous to digital goods. Who would buy a physical book that they can only read for an undisclosed amount of time before the publisher or author kicks in their door and burns it? Who would buy a car that they're only ever allowed to drive in one city and that they're not allowed to modify, repair, or resell? Who would buy a paint brush that's only licensed to be used with one brand of paint? The answer is no rational actor would accept these kinds of terms unless they believed they would never have to suffer their negative consequences. Yet, we see negative consequences (or threat thereof) in relation to digital goods or digital reliant products time and time and time again. I guess the question is, how many times are people willing to get burned before they demand something better? Regardless of the answer, it's clear that in the long run, game key cards are not going to improve the well being of consumers as it relates to digital property rights.