The question is overly subjective. I'd say its "quasi-vintage" if it applies to the original configuration, which is over 30 years old. The newer M24A2 configuration that I think is used by the US Air Force (and presumably various foreign military's too) is a more modern configuration. These are not my rifles, but the pic came off that thread I posted earlier. Top is a circa 1988 M24 and I'd call that 'quasi-vintage' as that was the best technology at the time (late 1980s). The rifle on the bottom was described as circa 2013 M24A2 - and I'd call that configuration contemporary/modern, as it is using some much new technology. (ie, newer optics, night vision/laser desginator/weapon light mounting capability, sound suppression, adjustable/ergnomic stock to accommodate various users and optics, detachable magazines, etc).
My guess is the M24A2 platform will extend the life of the M24 for military usage, esp in foreign countries like Israel and other foreign militarys that adopted the M24 back in the 1990s or 2000s, etc. So I don't think 'vintage' applies to the M24A2 configuration...
FWIW, when it comes to the local 'Vintage precision rifle match' held by Quantico's Shooting Club twice a year, the M24 in any flavor
is considered in the 'modern category'. The other categories are 1. vintage (pre-1953 per CMP rules), 2. Vietnam era, and 3. Modern.