No Marshmallow for Sony Xperia Z1 Compact

I was saddened to see that Sony is not intending to update the Sony Xperia Z1 Compact to Marshmallow. The reason is not clear but it could be due to the model being over the two years which google quotes to updating Android. I am disappointed because the Sony Xperia Z1 Compact is a brilliant phone and I did expect that the Z flagship phones would all be covered for this update.