Even if they’re magnetic and easy to swap, it sounds a LOT clunkier than just handing someone an iPad. People are going to lose the lenses all over the place.
Heck, my dad loses his phone multiple times a week, necessitating a quick phone call to track it down. Are the lenses going to include built-in AirTags so people can locate them?
I don’t have a proposal. I’m skeptical of the entire market for this product. I’m taking a wait-and-see approach and I’m looking forward to reading one-year followups from early adopters.
Heck, I’m even skeptical of the iPad. I own one and I use it so seldomly that I have to charge the thing up from 0 every time I use it. But I recognize that a lot of people love them as consumption devices and a few as creation tools for some niche purposes, such as digital painting.
Apple already does laser engraving for products bought in the online store. For the price point of this thing, they can probably move engraving into the retail stores (not long ago, I bought a laser engraver for my hobby 3D printer for a few hundred bucks -- they're not expensive, certainly not by Apple Store standards).
As for getting lost, Apple already has their AirTag technology. While I don't know if that's already in these lenses, it doesn't seem like it'd be difficult to add.
Likely the upfront issues would be getting everyone their personalized lenses, but actually using seems like it would be easy.