I don't think Apple needs to come in and rescue every display maker in the world with their branding. Any sufficiently high resolution display will do.
Once more displays come out with extremely high pixel density, we'll probably have an industry wide name for it.
Why not use the company agnostic term HD? You can be even more technical and say displays with 100+ DPI.
Also, your "more technical" definition is off by a long shot; people have been using 100-125 DPI screens for years, that's 100+ and it's not what would pass for a retina display unless it was 40" across and you sat at TV viewing distances away. Retina is being used in the generic sense to say "2X the DPI you're used too", or 250+ DPI for the current examples available. But even that DPI measurement is flexible because it's related to viewing distance.
So rather than stretching for generic terms that dont actually make it any clearer what you're describing, lets just stick with "retina" until we really have a better term :)
I threw a number out there, but should have known better since someone was to nitpick it.
The correct term is PPI (screens) over DPI (printers). Also, PPI is pixels per inch. PPI is not relative to viewing distance. DPI is not relative to viewing distance.[1]
An iPhone 4S has 326 PPI. We already have a technically accurate method to measure pixel density, so let's use it. Use bytes to describe data, not Libraries of Congress.
Retina is a marketing term. Does phone A had better PPI than phone B? I don't know, is Retina better than Super AMOLED++? Why not just compare technical details instead of resulting in fuzzy marketing word arguments?
[1]: DPI does not change with viewing distance, but the closer the viewing distance the higher the DPI needs to be to achieve the same visual effect. A billboard can look the same as a postcard at a much lower DPI because at that distance the human eye can't discern the individual dots.