Much of this work (and HTML5 in general) is about bringing the Web Platform up to being "equal" with "native apps". But one thing that the Web does that native apps can't do is deep linking (ignoring the fustercluck of intents). I think it would provide a significant advantage if it was also possible to deep link into installed web apps. I understand this is very complex and I'm not proposing any solution right now. But if we don't include this then we are in effect cutting web applications down to the level of native apps instead of leaping ahead of them.
Use Case: Social sharing
User A and User B both have the same web app installed on the devices they are using. User A finds a resource they like inside the app and decide to share this from within the app through one of their social networks. User B sees this link in their social feed and taps on it. Since User B also has this web app installed it would be "nice" to be able to open that resource directly within the installed app. Otherwise User X's browser would just open it like a normal web resource. This can also be relevant for the same user using the same web app across multiple devices.
NOTE: This is one of the key drivers we have found for building business cases of "Web instead of Native".
Elsewhere, Rob Manson wrote: