It seems that "medieval fantasy" no longer applies to D&D. It's more of a steampunk game,
Others have discussed the appropriateness of the term steampunk. Others have discussed medieval. I am going to address the 'no longer' part.
D&D, AD&D, playtest-era-proto-D&D,
Chainmail, and the supporting literature (be that Tolkien, Howard, Vance, or whomever) have all been quasi-medieval at best. Tolkien's hobbits famously had umbrellas, camping kettles, matches, clocks, pocket handkerchiefs and (in an early draft) barometers. They also had new world crops like potatoes and 'pipeweed' (although that one might be a deliberate tobacco alternative, explaining the otherwise-anachronism rather than highlighting it). Most impressively, the dragon firework is described as going overhead "like an express train." Other appendix N fiction varied all over the map, some of them being explicitly sci fi, or having a central protagonist being drawn from the modern era.
Chainmail and original
D&D had plate armor (a renaissance technology) from their inceptions.
Chainmail had firearms as well (although this makes sense regardless, as the fantasy element was an optional supplemental component). oD&D and AD&D didn't have firearms initially, but firearm rules were introduced in
Dragon #60 and
Dragon #70, as well as in the
AD&D 2nd edition Player's Handbook in 1989. AD&D did, however, have explicit rules for running crossover games with the other TSR properties
Boot Hill and
Gamma World, both of which included firearms (realistic or sci-fi/futuristic). More strikingly, sci fi elements (including robots, rayguns, and spaceships) showed up in Expedition to the Barrier Peaks, first introduced in the Origins II convention of 1976.
After that, we've had Dragonlance tinker gnomes,
Spelljammer trips to the stars, cthulian monsters from other galaxies (or beyond time and space), and any and every sci fi trope recycled and repackaged into fantasy elements any number of times, with no specific weight given to here-and-now. With the instigating moments being (as mentioned) right from the very beginning and every major introduction I can think of being older than many gamers. The last major new sci-fi or post-medieval addition to the game or breakthrough I can think of is the introduction of warforged as a default character race (in a specific singular game setting) -- which came out 20 years and 2.0 editions (I don't care how you count .5 editions, but they don't make it
fewer number of iterations) ago. That also was the era where I think the art deviated from at least the attempt at medieval aesthetic -- although whether the Liefeld-like buckles of 3.0 are more anachronistic than the Frazetta cover aesthetic of oD&D/AD&D is really a subjective position, I will allow.
So, no, I don't see any specific reason to think that medieval fantasy "no longer" applies to D&D, and certainly not specifically now or with the current version. It started out as fantasy with a medieval facade, peaked in its non-medieval-ness some time not now, and has arrived in the here and now not specifically more or less un-medieval at this point as any other.
