nokia was too ambitious with the lumia 920, and it is ambition that killed it
Consider the Nokia Lumia 920. This is a phone that can rightfully claim to be "the most innovative smartphone". After all, besides having flagship level specs (snapdragon s4, 32 GB storage), the Nokia Lumia 920 also has many different ways of differentiating itself amongst its peers. It has a pure motion screen, super sensitive touch,pure view camera, wireless charging, etc. These are features that you don't have on competing phones like the Samsung galaxy s3 or the Motorola Droid razr.
however, these features are causing Nokia a lot of supply chain issues. Nokia simply cannt make enough of these Lumias. This phone is still out of stock EVERYWHERE! It hasn't even launched in many areas, many of which are Nokia strongholds.
if Nokia tones down their ambition, and released the 820 as their mainstream flagship (with a 720p screen of course), make the current 820 the 720, and release the 920 as a niche product (like the pure view 808), they would have faired much better