Comment by xp84
13 hours ago
^^This.
Despite all the responsive design tools and declarative layouts to ensure a great layout even on an oddball resolution... the fact is that in practice it's nontrivial, and remember that the companies that make most of the apps you use have finite design and QA budgets. They need to actually use the resolution in question in order to really do a good job of designing for it, and giving them double the work, for a $2000 and up phone which probably won't be super highly adopted, is a recipe for getting apps that end up with layouts that aren't optimized properly on one (or both) of the screen sizes.
My point is largely that the nontrivial work you've described is the norm today. What's being asked for tomorrow is not new. Most apps are already set. Not just because of work Apple does to make it easier for apps to "port" out of the box, but because the multiple sizes that apps are already prepared to handle across iPhones, iPads, and resizeable iPad apps (and to the extent that devs are having React Native handle this, then across Android too).
So it's a lot of work, yes, but it's work that's already been done and that engineering teams already assume in their processes. The future is the same because this has been the status quo for a few years. Whether the Duo has a 2:1 ratio or something slightly different, the apps are at about the same readiness for it.