Since the sentence already contains the context of "technology"...
It is rather old, but _____________________ technology.
An adjective like well-developed could work.
Broadly defined, it means highly or fully developed, so it allows for the possibility that nothing is ever fully developed, so to speak (as previously suggested), and also permits the assumption that something may be...like my sixth hammer, obviously; the first five (all being the same brand, style, and weight)--'Misappropriated!'--carted off like Helen of Troy (Who could blame them?).
But hammers, even six of them, probably don't count as "technology"...
So, here's another example of fully developed technology found online, a video.
Well, that is some fine-looking machinery there...but I wonder if the wire-processing people thought their technology was fully developed before the invention of touchscreens. Hmm, it's just a thought.