I can't believe a new Lumia 15** type variant isn't destined around the corner.
Nokia is now Microsoft and there bound to want to introduce a new phablet flagship model on the Microsoft, Lumia or Surface brand name.
It has to happen, it's just when? I recon sooner rather that later.
Of course, no one from Microsoft's going to admit to future product releases, what would be the point, the longer a previous product can remain on the maket, that's sales revenue, the moment there's talk of a new and better product model, sales almost stop for the previous product line.
Also, current market prices for the Lumia 1520 shows it's price point has gone down, you can purchase the flagship model for almost ?300 uk, isn't a drop in price proof enough that something will arrive to match other manufacturers new build and price models.