Yes the three scenarios you mention are unlikely, and I agree that the web will continue to evolve rapidly for at least another five years. But isn't it possible for web apps continue to close the performance gap yet still lose their dominance as the 'first choice' for startup development?
For example, perhaps Google will make it much easier to port an Android app to iOS, similar to the way SWT makes it easy to write a single app that uses native controls on both Mac and Windows.
This Android+iOS app could then run on Windows, Mac, ChromeOS, Linux, Android, and iOS. Suppose that the cost of developing such an app is roughly equal to the cost of developing a web app. Wouldn't startups be tempted to choose this platform over a web app?
For example, perhaps Google will make it much easier to port an Android app to iOS, similar to the way SWT makes it easy to write a single app that uses native controls on both Mac and Windows.
This Android+iOS app could then run on Windows, Mac, ChromeOS, Linux, Android, and iOS. Suppose that the cost of developing such an app is roughly equal to the cost of developing a web app. Wouldn't startups be tempted to choose this platform over a web app?