I do see your point, though I do not share your particular concern, personally. (That does not of course invalidate your concern.) It may be worth pointing out that other phones have (and will have) under-screen cameras, so it's conceivable that you could find your available options diminishing in coming years, at least in the flagship phone arena.
I don't imagine this will meaningfully assuage your concerns... but interestingly enough, under-screen cameras
can be blocked, to some extent -- and you don't even need a sticker. The beginning of
this teardown video of one existing phone with an under-screen camera offers a glimpse into what I mean; if a bright color is rendered to the screen area resting over the camera, that color almost entirely obliterates the camera's view. To get the display to be as close to "transparent" as possible for use with the camera, you have to turn off the screen in that location, leaving at a minimum what looks like... a black hole in the display. Fancy that?
This necessity is why I've described the software interface for Apple's Dynamic Island as a "forward facing feature"; the under-screen Face ID sensors and camera will almost certainly continue to use virtually the same interface in order to black out the screen in the appropriate location when needed. The only question left for that is, how will Apple redesign the widgets that occasionally pop into view on either side of the no-longer-omnipresent Island? I imagine Apple already has a plan for that -- and hopefully it's a good one, but time will tell.
In any case, as I alluded above, I'm sure that there will continue to be iPhones (and other phones) without under-screen cameras for quite awhile, as the feature will obviously be restricted to the flagship/Pro lineups, at least initially. So you certainly have time to figure out what you'll be doing next, if Apple really does stop catering to your particular needs.