My current crop of players that I run for D&D know about that expedition to Dragon Mountain. In the Campaign setting I have been making for over 20 years now, the dragon is still there, and his domain is large, encompassing areas that once were human kingdoms and baronies, not to mention two elven forest kingdoms. My players want another crack at him, using 5E rules. They should; the last players there left a lot of **** good swag, including a +3 Sword of Sharpness and a Staff of Power (completely discharged in the fight against the dragon). I still have the maps, and I can't wait for them to try.

I've never played D&D, but that is one thing I really like about the system/setting - things can be persistent, and players have the chance to really leave a mark on the world.