Wilder went about that fight all wrong and he and his team know it. He was too heavy (231 pounds - up 19 from his usual fighting weight). He was trying to knock out a guy who is built like a brick outhouse who also had a reach advantage. Fury, in their first fight, tried to out-box Wilder and mostly did. He got caught twice and that's why it was a tie. Those two knockdowns should have signaled to the Wilder camp that they needed to refine his technique and box a smarter fight instead of trying to bully Fury. Fury's camp trained him to go after Wilder - take the fight to the bully - and it clearly got Wilder off his game.
How would they do against HW greats of the past? Hard to totally know but I'm inclined to agree with the lot of you that the current crop wouldn't do all that well. However, they are what we have and as a lifelong fan of the sport, I still keep up with what's happening in the HW ranks.
Where does Wilder go from here? Fury clearly wants Anthony Joshua (who is a straight up poser, btw). Joshua has two other fights he's obligated to before accepting that challenge. Fury-Wilder III would draw a crowd, but Wilder is going to have to wait in line. I expect Fury will schedule a bum to drop while he waits on Joshua and Wilder will probably get in a couple tune ups before taking another shot at Fury. If Joshua somehow unifies the belts and beats Fury, that's gonna spark an immediate rematch. By then, Wilder is going to be pushing 40 and may be done.