If it's PT-on, I doubt that SP will be as prominent as it is now. It will still be very good, but it will lose Uxie and Call, two of it's most important cards.
I got runner-up at Nationals with Luxchomp and I didn't play Call Energy. I think SP decks can still manage without Call. Uxie is a loss, but when you factor in the new Professor Oak supporter, I can still see SP decks working. Besides, don't ALL decks right now use Uxie? In a PT-on format, all decks would be slowed down equally, meaning that SP would still be a dominating force because of its speed.
It will still be prominent, but it won't be "OMGFIRSTTURNKILLLOLOLOLOLOLOLOLOL" any more. The number of true FTK decks will decrease significantly with both Uxie and Sableye out of the format. SP decks will still be utilized because they're generally fast, powerful, and consistent, and you can TecH them quite easily. But I don't think they'll remain as the "deck to beat". The format will transition slower, even if the entire SP engine is still around (I still hate Cyrus BTW), and slower evolution style decks will have at least a chance to deal with SPs before they really hit. Turn 2-3, rather than Turn 1.
Because starting with a Garchomp/DCE/Energy Gain (and being able to play it all with the new rules) against your opponent's lone whatever isn't "really hitting" on turn 1? Then, when the opponent plays a bench but can't Rare Candy into anything cause of the new rules, being able to Dragon Rush whatever you'd like isn't "really hitting" on turn 2?
I know that Uxie is the oil in the SP engine that helps everything run much more smoothly, but you can't tell me that SP won't have an advantage over an entire series of evolution decks that seem greatly slowed down. Rare Candy will be changed, GoW will be reprinted (meaning BlazeChomp might end up being the better play), and SP will still have the unbelievable advantage of teching against everything the format can throw at it. Zekrom popular? A single Promocroak will take care of that (and I'll Power Spray those CL Pachirisu thank you very much). Emboar popular? How about the SP Empoleon?
I mean, this is all a discussion we've had before: SP vs. evolution decks. There's a reason that SF Machamp
with Uxie still has a problem against SP's speed and disruption. So why do you think PT-on would be any different? Just because SP doesn't land a first-turn win (which, with the new rules, it would be even more able to do) doesn't mean it has no advantage over evolution decks. Why do you think that evolution decks without Uxie would be able to perform better against SP all of a sudden?
Additionally, if B&W sets ever comes out with a setup Pokemon (like Claydol, Pidgeot, Magcargo, Uxie, etc.), it'll just provide a new target for SP decks. There's almost no way that a setup Pokemon could avoid getting KO'd by SP, especially with Pokemon Catcher in the format. The only way it worked in DP-on was when decks ran 4 BTS/4-4 Claydol/2 Uxie... which to me was just more speed in the format. Otherwise, many decks ditched Claydol altogether and relied on a couple of Uxie drops.
No, I believe that if we continue with a PT-on format we'll inevitably continue with a format dominated by SP. It's been said that until SP rotates away, it will dominate the format. What would be even worse, however, is the fact that Japan would have no reason to produce cards that took away SP's dominant position in the format. People have complained about how lackluster HGSS-on sets have been, right? Well, it would the same for almost every B&W set as well if PT-on were the case. "Whoa cool, they reprinted FRLG Pidgeot!" "Yeah, but so what? I'll just play Luxray GL again."