I think you underestimate the market for high end keyboards. Kinesis has been doing this for a while for example and they don't seem to have a problem sustaining themselves or coming up with new versions. I bought a Kinesis Advantage 10 years ago for $350. They recently announced the Kinesis Advantage 2 for a similar price point. http://www.kinesis-ergo.com/shop/advantage2/
I'm sure it's not a huge market but it's enough to sustain a company that wants to focus on making premium accessories. I don't think keyboards are going anywhere anytime soon. Sure, the consumer market is shrinking but the average computer user was never going to spend $300 for a keyboard. People spend that when they do serious amounts of typing all day, and there doesn't seem to be a decrease in the number of people that need to type for a living.
I'm sure it's not a huge market but it's enough to sustain a company that wants to focus on making premium accessories. I don't think keyboards are going anywhere anytime soon. Sure, the consumer market is shrinking but the average computer user was never going to spend $300 for a keyboard. People spend that when they do serious amounts of typing all day, and there doesn't seem to be a decrease in the number of people that need to type for a living.