Please read to the end. I have played some of the games they were ok. This suggestion is not really for me, I have never played D&D nor plan to, but they would have some figures I would buy for sure. It seems to be making a come back, I know one of your competitors had the license and did a brick line that flopped but it was poorly done. It was targeted at kids and had nothing to do with the actual D&D game. It was created in 1974 and has no need of firing cannons at brick walls, it needs to be what the original creation had in mind.
With your style of mini figures the terrain molds from Dragons and wall molds from warcraft you have a lot of the parts already. If you were to do this targeted at the hobby level instead of kids it might take off well. Dungeon masters can build their own dungeons in 3d. They do this already but you give them the ability to make what they wish instead of premade builds. The hobby has stores dedicated to it around the world which helps with those distribution problems. TRU might be gone but there are hobby stores all over. You are targeting an age group that has disposable income and are already spending outrageous amounts on 28mm figures that have zero articulation.
With the new balders gate coming out and so many videos on you tube of games it also give you a huge advertisement opportunity. Mattel has a working relationship with the wwe already making the action figures. Up up down down does dungeons and dragons games with the superstars and I would bet they would be happy to use Mega's D&D highly articulated figures and someone build a dungeon from mega for them to run on their channel. I know this would be an adult theme line due to the monsters and the set dressing would not be able to be cartoony or it would flop.
If the actual license is impossible to wrestle away from whoever has it, you could still do a line of construction sets and figures directed to fantasy gaming. This would also bring eyes on the Masters of the Universe line for parts and figures as well. There are many on this forum that would hunt these sets down as well not to play D&D but for the orcs, gobbies, dwarves, amazons (see how i snuck that in there) and knights.
This line targets two groups in hobby players and construction builders both at the same time. However it needs to be mature or it will flop the hobby players will not go for something like yootz.