Rotations are delicate things. Rotate too much, and people get upset about how much money they spent for it to be useless so quick in tournaments. Rotate too little, and a few deck types end up dominating due to cards from many sets making a grand combination. Thus, it would be easy to look at some options.
PL-on: Everyone seems to love this format, or RR-on and it does make sense. Take out the DP packs, and have a nice, solid number of packs for the next BR and worlds according to how they release the packs. But, the one problem is SP decks will be dominating even more. It is unknown, though, about the next pack coming out having some kind of draw engine like Uxie or Claydol, thus, SP's may not dominate for too much time. Yes, the argument of SP's using Uxxie and Claydol are true, but they still have Cyrus' and all of the SP trainers. Thus, unless blocked by spiritomb(Most SP decks have ways around, however), they have plenty of ways to acquire their cards. This is the most likely one, through all complaints and cheers. This or...
SF-on: Some have mentioned this. Interesting why people want to keep Machamp in, yet kick out Unown G. This balances out some of the SP dominance, and keeps some favored cards in the set, also leaving a nice, solid number of packs to go off of. This also keeps Heatran lvl X for burn decks, and Dusknoir lvl X for Ectoplasm. This is an interesting choice, and I think it will work out to an extent if they choose this. Though, it would be odd to only keep one DP pack and kick out the rest, wouldn't you agree?
RR-on: This one is what interested people the most. They figured out if they kicked out all of the SP only trainers, it'd balance things out and make SP's not so dominant. But it did it a bit too well. Without many of these trainers, SP decks will be slowed down tremendously, causing them to become more rogue decks instead of winning almost all tournaments. No Uxie, Claydol, Azelf, or SP trainers. It does, however, leave a nice variety of packs for the next BR. Though, perhaps kicking out one platinum pack, and keeping the others doesn't seem to good.
HGSS-on: This is, most likely, the worst choice. With only 3 packs for BR, you get little to no variety at all, not to mention knocking out cards which barely had a time to shine. Now, you get to see what's left. Maybe a jumpluff deck, and otherwise just Feraligatr and Blastoise. This format makes almost every deck extremely slow with no Bebe's, Roseannes, Claydol, Uxie, Azelf, or any draw or search engine we use now. You get collectors, pokemon communication, and Ninetales. Potentially Interviewer's Questions and Engineer's adjustments. That's about it.
Other choices may be interesting, and I'd love to look some information up on them if you bring them up, but most other's don't seem too likely. POP still need to balance their packs, after all. Too many can lead to a disaster, though I'd personally love to see no rotations. I do hope you enjoyed my theories on how each of these rotations might effect things, and if I missed something, tell me. I do not wish to have a theory that is lacking information that could be very helpful.