Consider doing an invention evaluation study. This can help you gauge overall consumer interest in your hardware, if indeed it's consumer facing. If it's not, then a full market study might be the way to go. However these studies are significantly more expensive. I'm happy to talk with you about managing either.

I have to say that to answer the question more fully would be a consultancy project... But I can give you some brief information.

You can find some brief information about consumer penetration in US: http://4k.com/news/4k-tv-sales-to-surpass-100-million-units-by-2018-5948/

Services available in 4K: http://www.wired.com/2015/02/live-4k-broadcasts/

Netflix is the only current service delivering 4k, with Amazon testing delivery. The trouble with it is the same as HD, though: a HD stream can be 10Kbps. The specification is useless: what counts is the lowest point of the data rate between source and viewer.

Looking at the H265 codec specifically, there is a major move to usurp this http://www.theverge.com/2015/9/2/9252753/alliance-for-open-media-next-generation-codec

Basically all hardware in the delivery chain needs replacing for 4k, so it's likely to take 6 - 10 years to become mainstream.

In my opinion the main argument for HEVC is to future proof content, but if it's not produced in 4K then there is little benefit.