To recap, WP running Android apps has the following benefits:
- We may get the Android version of [name of cool app] on our phones
And the following problems:
- We will get the Android-specific version of [name of cool app], not one that looks like WP or uses WP-specific features
- Which may be buggy due to differences between the MS runtime and the Google runtime
- Which won't support live tiles and WP won't support widgets (key for me personally)
- Which may not arrive at all due to Google services integration or other issues that the dev doesn't want to spend time to fix for only 3% of the market
- Android version (ex. 4.4 Kitkat or 4.3 Jellybean) on WP would lag behind real Android by 6 months at best, years at worst
- Windows Phone 3rd-party development would essentially stop
- Even MS-focused devs would stop making WP (and possibly Windows) apps and concentrate on Android or worse, iOS (which wouldn't run on the new WP at all)
- WP phones start to use more battery and become slower with the additional runtime overhead and Android's notoriously resource-intensive background task overhead
- Consumers get confused because of app availability and compatibility problems compared to standard Android devices and WP devices get a reputation as buggy
If Microsoft is betting in Android apps they could add APIs to take advantage of the features of the platform (Live Tiles, Cortana, XBOX, etc.), and custom UI components to match the Metro design. Buggy apps shouldn't be accepted in the store.
There are still incentives for native development:
*If an Android apps don't work well (bugs, performance or lack key features of the platform), It's a big incentive for native development. With a low quality app developers don't make money.
*Android apps will help with the perception of the platform, the market share will increase. If WP grows to 5% of market share, that's 100 million people, an interesting niche to target with a good native app. The bigger the market share, the bigger the incentive for native development.
*Developers still have to work in an app for Windows tablets and desktop, even XBOX. Universal apps is another incentive for native development.
*Microsoft can choose what Android apps will be accepted in the store, define conditions, add incentives to move to native if an app become popular.
*Microsoft has to use resources, (money, developers) to guarantee native apps for the key services in which users spend most of their time. Facebook, Twitter, Instagram, WhatsApp, etc. So, 80% or more of the effective usage time has to be a high quality native experience.
Android apps are going to help this platform to take off. Without Android app It'd take years or maybe WP could die.