Here are my thoughts, but my plan is flowed beacuse I don't think there are enough openers here/maybe people think certain bands should be higher. I'm not a fan of all of these bands, but was thinking in terms of prog-power mix and Glen's taste.
Debut:
Pretty Maids - headliners
Labyrinth or DGM - 2nd/3rd spot
Vanishing Point - 2nd/3rd spot
Astral Doors - 2nd spot, the Intromental band for this year
Serenity - opener
Machine men - opener
Been to US, not at PP:
Within temptation - finally this year, continuing the trend of at least one female band (4th)
Amorphis - sort of re-ignited their career (3rd)
Returns
I think Circus Maximus is a lock (2nd/3rd spot). But potentially Brainstorm (4th spot) since they'll have a new album
And since Glen has been doing some pretty creative things (like the Jam), I predict for the 2nd returnee, he gets AVANTASIA show as headliners. They're gonna tour and headline Wacken, Glen call pull this off in the States
Of course all of this IMHO for fun and games.