Microsoft separates Windows Phone 8 updates into major and minor ones – so far we've seen one major (8.1) and three minor ones (GDR 1, 2 and 3). The company is reportedly planning at least two GDR updates for WP8.1 this year.
That's wholly unconfirmed for now, but a 3D Touch system is a possibility. We heard the first murmurs about it last year – it's essentially Samsung's Air Gestures from the Galaxy S and Note devices, at least that's what the first rumor made it sound like.
Another possibility is evolving Nokia's Refocus app (which got many imitators in this flagship generation). The rumor mill is talking of a dual-camera setup to create Lytro-like refocusable photos with just one shot. HTC tried just that and the results were not perfect.
The first of the GDR updates for Windows Phone 8.1 might come in the middle of this year (June/July) and the second one towards the end (November/December).