I think the whole thing is a non-issue.
There has always been a distinct difference between consumer and professional formats, be it Beta vs. Betacam, DVC vs. DVC Pro and now 4K vs. 4K Pro.
Heck even in the SD days, the home version ran considerably less than 480 lines compared to professional SD formats.
At least the tech this time seems to be settling on one version of consumer 4K instead of the potpourri of HD formats in the consumer world, such as 720p, 1080i and 1080p (often billed as "full HD").
I'm just not seeing the issue here. Consumers that don't understand it, won't care and those that care are going to know the difference and can make an informed decision based on that knowledge. I say, let the rabble have their "4K" and those who actually create the stuff can use a grown up "Pro" version. Heck, even if the just differentiated with "4K" and "4k" people who know this stuff would figure it out.
As far as people not knowing the difference between 4K and Mastered in 4K, those people can bite me. The "mastered in" terminology has been used since DVD when those titles were "mastered in HD". If people still don't get it, they deserve what they get. I'm tired of pandering to consumers that don't bother to find out what they're actually buying.
Buying a descriptive term is why it's becoming impossible to buy a real 4 wheel drive vehicle that isn't simply all wheel drive anymore. Of course, just like consumers who often don't display HD on their HD displays, most of those same people probably never take a 4WD anywhere further off road than a gravel driveway.
Just stick to one name and avoid confusing the lemmings with the whole 4K vs. UHD thing. If people are confused, they won't buy it. If people don't buy it, we get screwed when the studios don't put out content for it.