Microsoft respects customers. So I believe they will finally give the update. Maybe not too official and not through the "over the air update tunnel " but they will give it. With lumia 920 & 925 are in the same problem and I hope MS will not disappoint us. I have 5 windows phones in my family. . Only one of them has windows 10.
MS have long forgotten about this matter and nobody is wasting time or effort working on W10M updates for the phones which do not already support it.