At least 3D won't die overnight. The movies do sell fairly well in some markets (which is why almost all my 3D Blu-rays are for Europe and Australasia). Just not in the big American one for... lots of reasons from how poorly 3D was implemented in sets to how costly and difficult it was to acquire the content. But 3D has died multiple times. It will be back. Each time it comes back it's better than before. It may be another 15 or 20 years, but we will get our 3D again, and it'll be glasses-free, multi-perspective, and possibly with multifocal depths.
3D was DOA because watching 3D movies didn't add any value to the storytelling. It might be back, but really the issue hasn't been technological, it just doesn't add enough value to get beyond gimmickry.