Both approaches look very promising. We already signed up for the Project Astoria developer preview.
I hope the brigde will include 100% of the phone's functionality (also Bluetooth Low Energy, background tasks, ...). Otherwise it would be worthless for us and many other developers.
We already know the concept of an Android bridge from Blackberry, where it works very well.
Still we cannot publish our new release of Run.GPS for Windows Phone, because Windows Phone 8.1 does not allow background location tracking. Also, there's no information if it will come back with Windows Phone 10. They just killed a whole branch of Windows Phone apps (outdoor sports apps).
If you want to help us, please vote for background location tracking to come back in Windows Phone:
11.12.2014 09:28:31 UTCgeändert am 31.03.2015 09:10:28 UTC
Amendment to our newsletter: Windows Phone 8.1 Applications
The statement in our December newsletter regarding Windows Phone 8.1 apps was not very clear, so let me try to clarify it.
It's no problem to run location-based tracking apps developed for Windows Phone 8.0 on a Windows Phone 8.1 phone. This is true also for Run.GPS. So you can continue to use the app you have paid for, of course. The problem is that we cannot develop Windows Phone 8.1 native apps with background location tracking. Which means that we cannot use the Bluetooth 4.0 API, which is only present in Windows Phone 8.1.
Our Windows Phone 8.1 version of Run.GPS had been finished a month ago and is working great - but it cannot be published because the WP8.1 policy does not allow for apps with continuous background location tracking. It's not a technical problem, but a problem with app publication policy.