Will Windows Phone 7/7.5 apps work on Windows Phone 8?

Since Microsoft has not released the Windows Phone 8 SDK toall developers yet, it is reasonable to assume that there will be a relativelysmall number of native Windows Phone 8 apps to be available once the OS makesits launch.  Such a reality is notuncommon with any operating system. Microsoft promised that Windows Phone 8 would allow any Windows Phone7.5 app to run without modification. 

What may pose a problem is how the language coming fromMicrosoft is not sounding so confident.  Somewere openly wondering if the delay of rolling out the SDK to everyone might be relatedto keeping some features locked down until closer to the officialannouncement.  What may be more likelyhowever, is that there is a backward compatibility problem.  Windows Phone 8 is a clean OS break from itspredecessor.

In a September 12 blog post by Andrew Whitechapel with theWindows Phone Developer Blog raises the issue of compatibility in his first bulletpoint:

Now let us couple the blog post with what was said in aSeptember 17 podcast, Windows Phone Product Manager, Cliff Simpkins is quotedas saying:

Assuming this is the real issue, the question of “why”remains unanswered.  Or, this could bethe grand Microsoft plan to keep us all in suspense until everything isannounced.