Let's see... As far as repeats go, obviously we can rule out all PP4 bands. Don't forget that PP2.0 bombed, sadly, so bands like Superior and Balance of Power are pretty unlikely candidates IMO. Objectively speaking (read: never mind how much I'd give to see them again

) I think Threshold are highly likely as long as their own schedule allows it. They were incredibly well received at PP3, and I'd bet good money that Glenn is trying to get them again.
Pain of Salvation is always a crowd-drawer... Well, okay, that place was empty after Blind Guardian, but they are popular. Speaking of BG, I wouldn't rule them out, either... Edguy went over very well with everyone buy me at PP3; sorry, I couldn't even make it through the first song. I can easily live with them if it gets Threshold back. So, my prediction for repeats: Threshold and PoS.
As for bands that have never played PPUSA before: Tad Morose have been mentioned, and I think they're a good possibility. Sonata Arctica are a no brainer IM-somewhat-uninformed-O, as long as they can come to an agreement with Glenn and schedules work out. Sonata Arctica and Edguy on the same bill... Blech. But I don't give a shit if it brings Threshold to our shores again.
As for female fronted bands, The Gathering are a possibility and would REALLY draw ticket sales. I n fact, if The Gathering, Sonata Arctica and Pain of Salvation are all on the bill PP5 will sell out in 24 hours, mark my words. Personally, for a female fronted band I'd give my left nut to see Sinergy, who IMO (as I make yet another lame attempt to read Glenn's mind) are a good possibility if The Gathering are a no-go. Remember, the Gathering *have* toured the U.S. before, but they reeaally didn't like it IIRC. Of course PP is very different than playing dives, so Anneke and the guys might be up for it. If they play Mandylion in its entirety I'll take them over Sinergy, but obviously that's not going to happen.

There's many other FF possibilities, too: Lacuna Coil, After Forever, etc.
Someone mentioned Shaman, and how they make sense after Angra have already played.
So from these bands and a few others, I'll predict:
1. The Gathering (headliner, night two)
2. Sonata Arctica (headliner, night one)
3. Pain of Salvation
4. Tad Morose
5. Edguy
6. Threshold
7. Shaman
8. Seven Witches
9. Riot
10. Pretty Maids
We'll see how wrong I am in a few months...
