Nah 3D has always been a gimmick that has weaved in out of popularity for the past 50 years.
4k I just the natural evolution of pixel density, but you are absolutely correct, the issue is whether or not enough content
will be shot at a 4k resolution to warrant it. As of today, 99% of broadcast intended content is shot in "HD" in the US isn't even 1080p. It's almost entirely 720p and 1080i (PPV events being the sole exclusive).
Regardless, buying a ~55inch+ TV at 1080p is just silly now. The pixel density would be too low for such a large viewing space. I have a 60 inch TV right now (I regret it) and I'm just waiting for 4k to drop in price to replace it