I'm looking at mike_hearn's response in the thread, and it's going in a good direction I think (https://hydraulic.software), albeit platform owners would need to do a lot more to help that kind of approach to succeed.
Looking at the current situation from a high level view, we already have URLs for applications (you'll need to declare a unique identifier for your bundle), and Apple and Google are already toying with the idea of immediately executable apps with App Clips and Instant Apps, so it feels like we're actually pretty close from that alternate reality where "installing" can be seamless to the user.
(+ iOS also handles removing unused apps from the device, so that part should also be ok)
Looking at the current situation from a high level view, we already have URLs for applications (you'll need to declare a unique identifier for your bundle), and Apple and Google are already toying with the idea of immediately executable apps with App Clips and Instant Apps, so it feels like we're actually pretty close from that alternate reality where "installing" can be seamless to the user.
(+ iOS also handles removing unused apps from the device, so that part should also be ok)