I think they will, especially "first" models or high end units. Higher end walkman from 80's-90's are already very expensive (and old new stock high end tapes too), first gen ipods and iphones are expensive af, same for minidisc players, even old portable CD players (the top models at least) from early 2000's are increasing in price as well. Even tho it is usually impossible to get their proprietary batteries for them anymore.
I am kinda angry that I missed the sweet spot to get the last G5 powermacs when they were still selling for nothing.
I can easily see things like first foldable phones, or first gen m1 apple laptops being collectible items in 20 years
The only problem with smartphones is that due to rapid change and closed ecosystem, old units are becoming just display pieces, as it is impossible to use first gen android devices for anything other than making calls, because factory default apps like maps or twitter no longer connect to the services they are based on, and new versions won't instal on old android.
to add to thread's topic: I miss when burning CDs was a thing. It was such a magical thing to see the progress on NERO burning rom. I always wanted a LightScribe drive, but thjose were super expensive. I looked into it recently, and you can get them siomewhat cheap nowadays, the problem is that they don't make lightscribe CDs anymoe