There is interest in the use of hybrid tools (e.g. Titanium) that help develop applications by leveraging both options – i.e. develop parts of the application using mobile web and other performance-heavy parts using native app methods. Such tools tend to reduce the device specific code content in mobile applications by leveraging mobile web wherever appropriate although complexities behind supporting hybrid applications that mix and match mobile web and native code are yet to be understood.
I think that proprietary mobile device platforms are here to stay and will actually reverse the benefits from open server consolidation (for example, migration from proprietary UNIX versions to open versions of UNIX that can run on proprietary hardware platforms). However, software tools and products for mobile application development that commit themselves to open source and standards to help minimize the differences between proprietary device platforms and make it easy for developers to support mobile applications on multiple devices are likely to succeed in the future.