Struck a nerve with three words, huh.
To start, calling Dion Waiters a budding 20ppg scorer is silly. In order to do so, he needs to take close to 20 shots a game-- even in his best month (March), he shot about 18 times a game and scored about 19. He's an inefficient scorer, and always has been; you'd be surprised how many guys could equal his production if they took the same number of bad shots. Overlooking his inefficient ways of scoring reeks of homerism.
I'm also not exactly sure what you mean by Dion "can play defense". He's currently worse than Kyrie, an awful defender, in defensive win shares, defensive rating, and steal%. To top it all off, Dion is a pretty bad rebounder. Now, he's better than Kyrie, and is no slouch. He can "play defense", just like many other guards in the NBA can. He's not special on that end of the floor by any stretch of the imagination, though, and is still prone to mental mistakes due to immaturity. Not sure where you're going with that.
Now, let's talk about Drummond. It's common knowledge that centers are the most coveted types of players in the NBA, as truly good ones come around very infrequently. Drummond, from a defense/rebounding perspective, is everything you want in a center-- dominant rebounder, and can anchor an elite defense with his size and shot-blocking. Roy fucking Hibbert just practically got a max contract while having no offensive game to speak of; these guys are so so so much more valuable to a team than guys like Dion. I'm really shocked you're even having me tell you this. And while Drummond is certainly raw offensively, he's still averaging 13ppg in about 32 mins. That's still great production, and he'll improve over the years.
Your projection for Dion is based on a small sample size that isn't majorly impressive when you look past the sheer numbers (not close to being equivalent to Drummond's production), and an abstract concept that he's "harnessing the chip on his shoulder for the better", which is quite the leap of faith given A) he's been an immature player his whole career and B) we've seen flashes of growing up from multiple players on this team, only to see them fall back to previous levels. Go ahead and hop on the Dion bandwagon after a month of him being different. I'll wait a bit longer, thank you very much.
I'm not dismissing the possibility he could ultimately be better than Drummond. I'm calling it idiotic to put the odds at 50/50.