what part of "nowadays" and "sold" don't you understand?
Any evidence of that? A quick look at Argos shows out of a total of about 200 models for sale, 35 are 3D capable, and Googling the subject finds nothing suggestive of a majority of TV sales being 3D capable.
Secondly, the point is that, regardless what proportion of current sales are 3D capable, it's the actual adoption rate that matters. eg. If 100% of TV sales are now 3D, but sales of TVs sticks at only 1% of the national install base for years because everyone's happy with the HDTV they bought recently, the actual proportion of 3D users would remain extremely niche for ages.
Lots of people have recently upgraded their CRT to a slim HDTV, the final adoption of a standard introduced over a decade ago. This improved resolution represents approximately the limits of visual fidelity for a lot of homes given screen sizes and viewing distances. 3D adottion, the latest standard, has seen predictions like 25% of UK homes could have a 3D TV in 2015. Given that:
1) this generation of consoles had trouble hitting 1080p. The first doubling of power from this gen to next will be used up just to hit 1080p, ignoring the power requirements of rendering better visuals.
2) 4k is a resolution that very few people could actually benefit from so they have little incentive to buy a 4k screen
3) the storage requirements of 4k data are extreme, while no movie content is made at that resolution, so there's nothing much to be gained with movies
4) people have only recently (past ten years) upgraded their TVs to HD sets, with very few also upgrading to 3D, and 3D is the current big push with people buying new 3D so less lucky to go and buy another new set that offers 4k
5) there's a worldwide recession impacting people's buying habits
...how likely is it, really, that 4k is going to be a target for consoles launching in the next few years?