I don't disagree with your idea, but unfortunately there is always going to be that churn. Commercial device/app developers have
lots of money to invest in robust development and advertisement, to beget the return of more money. Meanwhile, the economic benefits to preserving people's autonomy (/dignity) is spread out amongst those people. Which is why in another comment, I called it a "zero" million dollar idea.
The flip side is all of this device churn is all the actually devices left in the wake, available for cheap/free. If software is done right, even last-decade specs are perfectly capable devices good for another decade. Which is what we need, because convincing someone to pave over their current device or spend a lot on a new "weird" one isn't going to happen. Tablets got a foothold by being a new type of device, rather than an immediate replacement.