you can not generalize the market share to less than 0.1%, because Microsoft has not promoted globally its phones
A fact is fact, regardless of how MS promoted or did not promote their phones. 0.5% or even 1% in a couple of countries is still completely irrelevant, plus the numbers are dropping each day.
Windows Phone is on the radar even if the competition delivers over 1.5 billion devices
No, it's not on anyone's radar except a handful of die-hard fanatics which are irrelevant. It cannot be on the radar if no devices have been released in over 2 years and the platform was officially discontinued.
a functional & sustainable phone
Functional yes, with functionality being reduced on a daily basis. Sustainable definitely not.