Unless Tizen can flawlessly run Android apps, its going to fail. Platforms successes revolve around Apps, whats the number 1 complaint about Windows Phone right now? Lack of major apps. Blackberry 10 can emulate them, but it's only Android 2.2, and it's far from perfect.
The only way I'll see it succeed is if Tizen has the Google Play Store with it, and you can simply download and run Android apps like native.