There are two sides to it, one from the consumer's POV and other from the company's perspective. We already have a lack of HD content through most of the DTH STB providers and 4K and 8K's won't help there because of their 4 and 8 times the resolution. Plus the costs involved would put them out of reach for the majority of consumer base. To put simply, the relevant content will be unavailable for quite a few years to come. But from a manufacturer's thinking, it is an investment that is going to help them to perfect the technology and reduce the production costs of these TV's for its target audience as and when 4K and 8K content becomes available. The Panasonic 8K hasn't gone into production yet but LG and Sony's 4K 3D TV's should be in the market very soon.
The Panasonic 8k set is 145" and will probably sell for well over $100k. Not intended for home use but for industrial and business applications. The 4k LCD panel sets seem to be all based on one Chinese manufacturers panel. Pricing looks to be in the $20k range, sizes seem to be about 70" or so. The additional processing needed to convert to 2k will not help the picture quality and most people will not sit close enough to even see the difference in resolution.