There is the complication that the Byers family (now including Eleven) moved away from Hawkins, so the former D&D party would presumably be made up of Mike, Dustin, and Lucas, with maybe Erica and Steve for good measure.
The guys had moved away from their epic campaigns by the time they hit the summer of 1985 in Season 3, but they could get back into the game for Season 4.
The dice alone point toward D&D, and flaming swords and morning stars can be wielded in D&D.