My comments were specifically about the uniform pictured, not any other type since that's a much larger discussion to have. But since the discussion has been broadened, for sure the airborne version was apparently worn pretty much right up until the changeover to Woodland. I have some examples that were manufactured in the 1980s, while the dated examples of the standard infantry version I've seen were 1960s and 1970s vintage. As for the infantry version being used longer for "elite" units, that wouldn't surprise me. However, I've seen quite a number of pics of regular Infantry wearing the OD uniform in the 1980s, so it appears to be transitioned out of general use prior to Woodland.
I also have BSM uniforms manufactured in the 1980s, so I'm sure that was in use until the changeover to the airbrush pattern.
As far as the infantry version being intended to be an oversuit, I have zero doubts that is exactly what it was originally supposed to be. The trousers have pass through hand pockets without any sort of fasteners or integrated pockets, which is the hallmark of an over garment. The integrated suspenders, instead of a belt, is also an indication of an over garment. The jacket is heavily bloused and has an elasticized lower hem, which can't be worn inside the trousers. This is, again, a common feature of over garments and not a common feature of a stand-alone field jacket.
Now, what soldiers do with the uniforms they are issued is an entirely different matter. Oversuits tend to be a terribly impractical arrangement and that means soldiers will adapt them to be more useful. The Austrian dot camo was designed to be worn over a wool field uniform, but it rarely was because only a sadist would think that was a good idea
So I'd say the evidence suggests the uniform was intended to be an oversuit and that soldiers likely disregarded this when it was allowed.
Note that the airborne version is very different than the set pictured here. Unfortunately, many resellers call the infantry version airborne because of the integrated padded knees and elbows. The airborne version does not appear to have been intended as an oversuit.