Just because we haven't gotten a leaked rumor of a new flagship coming down the pipe or whatever, doesn't mean MS hasn't been working on one. If Microsoft has stopped production, then they may just be trying to finish selling what they have before they gear up production of a replacement. Makes perfect sense in a business world.
If MS were to announce the 1530 would be available in February or March, then no one would buy the 1520 now, and MS would be stuck with a lot of stock it can't get rid of.
I'm an optimist (probably because Verizon isn't my carrier), so I choose to believe this is a sign that a new flagship is on the horizon, and most probably within a 6 month time frame. Whether or not I'm right or wrong doesn't really matter to me, because it will be out eventually. I still think the 1530 has a good chance of shipping with Windows 10, though, but if it does, it may be further out than 6 months.