I'm not sure about the nice argument. The reason some people got fed up with Johto!Gary is because he was a total arsehole to begin with and then changed into a nice guy. So the people who liked his original, gittish personality were biased in its favour. It's a bit like the fans in the Buffy The Vampire Slayer fandom who got p*ssed off when the writers redeemed Spike. But Drew's always been on the side o' good - that was made clear in his first episode - so there's no reason why anyone would complain about him unless they just never liked him to begin with. And in any case, we have Harley around now to be May's evil rival, which should tide over the people who can't stand the protagonist and his/her main rival becoming friends.
Speaking of Harley, I don't think May will beat Drew while he's still on the show. Since his first appearance, Harley's turned into May's main antagonist. The writers have focussed more on May vs. Harley in recent episodes than they have on May vs. Drew. Examples:
A Cacturne For The Worse - Harley's debut
Introduces Harley and establishes his hatred of May. The whole episode revolves around Harley's attempts to make May lose the contest, ending up with a big battle between them that May wins. The focus is exclusively on May vs. Harley.
The Wynaut of Mirage Island
There's some May vs. Drew stuff at the beginning, where they both show off their ribbons and start up a Pokemon battle, but before long Team Rocket show up, the entire group is blasted off and lands on the island, and May and Drew are separated from the others. The rest of the ep is about them working together to stay alive, bond with Wynauts, rescue the berries, fight Team Rocket, etc. So this episode was more about the May-Drew friendship.
The Grand Festival
Might as well lump all three episodes in together. The GF was, for the most part, all about May vs. Harley. For the first two eps, Harley hangs around with May, pretending to be her friend and trying to sabotage her. Eventually she finds out the truth, and she battles and defeats him in the third ep.
Drew, however, spends most of the time spying on May from a distance, clearly disapproving of May/Harley but not antagonising May at any point. He once tries to get May to stop being so friendly with Harley by telling the both of them that they shouldn't be so open with their opponents, but otherwise hardly even speaks. When he re-enters the story, it's to overhear Harley gloating over his successful attempt to trick May, confront him and tell May the truth. He turns into her ally against Harley at that point, though immediately afterwards he yells at her and stalks off.
The final episode includes May battling Harley and Drew, so both rivalries are featured. However once she loses the match to Drew, she goes on to root for him in the rest of their matches (she's very disappointed when he loses to Robert), and has a couple of moments with him later, one at the closing ceremony and one at the party afterwards. The second of these, incidentally, is when Drew announces his intention to some day beat Robert, introducing a whole new plotline into the mix.
So overall, the Grand Festival was mostly about May-Harley rivalry and May-Drew friendship, with a comparatively small amount of screentime given over to the May-Drew rivalry.
Catch Arcanine! (can't remember the proper title)
Drew's back, he and May spend the ep competing over who's going to be the one to capture Arcanine, and they even have a battle that they actually get to finish (gasp!). But in the end, they team up to blast off Team Rocket and save the Growlithe family, and both of them agree not to catch Arcanine after all. So it's kinda rivally, but kinda not.
The Saffron contest
Both episodes, again, are all about May vs. Harley, ending in that infamous Squirtle vs. Ariados match that so many people hate so much.
So ever since Harley came onto the scene, he seems to have turned into May's main rival, while Drew... hasn't been pushed into the background exactly, but there has been a definite shift in the May-Drew dynamic.
To get back to the topic, IMO what this means is that for now, the writers will probably carry on focussing on May vs. Harley. I don't think there's any possibility of them not facing each other in the Kanto Grand Festival, or of May not winning when they do. And since neither Ash nor May have ever beaten two important rivals in a contest (with good reason, it'd mess up the pacing), it doesn't seem at all likely that May will go on to beat Drew right after Harley. In fact, it would be a disservice to May vs. Drew to have it occur almost as an afterthought in that manner. Drew was introduced as May's main rival, and IMO May won't beat him until after he's become her main rival again - which won't happen until after Harley's left the show.
So what I imagine will happen in this year's GF is that Drew will lose to another trainer - maybe Harley, that would be interesting, or Robert - while May beats Harley and then loses to someone else.
Once Kanto is over, though, I imagine the writers will probably resolve May-Drew in the D/P region, unless they come up with a very inventive way to keep dragging it out.
