I'd argue that portability is a non-issue. iPhone developers know that to make sales to iPhone owners, their applications have to visually and functionally integrate seamlessly into that environment. The same is true for Android owners. Anyone writing a portable HTML5 application is at an extreme disadvantage. And the fact is, the effort necessary to make an excellent mobile browser based UI that integrates seamlessly with multiple platforms is more work than simply rewriting the app for multiple native platforms.
That depends on how many platforms there are. If it's just Android and iPhone then the native apps just need a few perks to make it more attractive. On the other hand, if there are 5 reasonably balanced platforms that all support HTML5 well, then you are automatically cutting your market size by 80% which is a tougher call.
> And the fact is, the effort necessary to make an excellent mobile browser based UI that integrates seamlessly with multiple platforms is more work than simply rewriting the app for multiple native platforms.
Today. But HTML5 will steadily improve, standardize, and develop a rich open source tool ecosystem. This will never happen with proprietary native platforms. Sure Apple can go the Microsoft route, and sink an incredible amount of money into it's dev tools in order to create a superficially better experience, but if web development is anything to go by, developer tools are something that thrive on open collaboration; very few people would say that .NET is generally superior to open source web development frameworks for example.
I'd argue that portability is a non-issue. iPhone developers know that to make sales to iPhone owners, their applications have to visually and functionally integrate seamlessly into that environment. The same is true for Android owners. Anyone writing a portable HTML5 application is at an extreme disadvantage. And the fact is, the effort necessary to make an excellent mobile browser based UI that integrates seamlessly with multiple platforms is more work than simply rewriting the app for multiple native platforms.