Maybe, but one loom on deviantart proves that the rule 34 community does NOT need to be spurred on.I hope to Arceus they include character customizations. That would make Hoenn perfect. The region of water? Beach wear, heck yes!
I can assure you, GF will not factor in rule 34 when thinking of designing outfits for the protagonists.
Why?
Because the rule can be applied regardless, as Fairy Type Arceus said. That's WHY it's a rule. You can ALREADY find the Pokemon protagonists in beach outfits, just google search it.
Heck, you can find applications of the rule on CARTOONS. No, not anime, I mean actual cartoons, like Spongebob. So of COURSE it would exist for Pokemon.
Fair enough. Just be prepared ^_^
You say this AS IF there isn't already "rule 34"-esque content for Pokemon characters (and for the Pokemon THEMSELVES, mind you). There's nothing to be prepared for, it ALREADY EXISTS. Don't believe me? Google it.
Actually, I doubt people would make more of such content when it does exist, cuz there's no point. There's SO MUCH of it, it's gotten to the point that if you do a regular google image search (e.g. "Misty"), you'll find it within the first 10 results.
Anyway, back on topic, as @Fairy Type Arceus; said, GF will not let Rule 34 hinder their character customization.