Let's dissect and come up with an idea of what First Tier actually means.
For all intents and purposes, "First Tier" would not just imply a band you want to see or a select few forum members want to see, the "First Tier" bands are the bands that headline, the bands that sell all the tickets, the bands that get people to travel, the bands that make it special. I love some of the bands listed thus far as 1st tier, but would sadly say no to them as First Tier. When they were active, I would hardly call Lost Horizon a first tier band. Brilliant, yes. Superlative even. But...they do not have the broad audience that an Angra, Stratovarius, Blind Guardian, Iced Earth, or even an Amorphis have.
And let's face it: there aren't that many first tier bands left that HAVEN'T played already. We'd have to dig deep. Either Glenn gets a "First Tier" band that's been around since the '60s/'70s/'80s (Saxon, Pretty Maids, Scorpions, Manowar, etc.), he gets one of the very very few remaining big name power metal bands (Rhapsody, Demons & Wizards, Grave Digger, Running Wild), he somehow manages to get something impossible (probably Avantasia, Ayreon/Star One, Control Denied reformation/reunion), or starts to branch out to other forms of metal (a la Arcturus...bands like Ihsahn, Opeth, Pardise Lost, Anathema), or get rid of headliners altogether (not likely).
I think losing the pool of "First Tier" bands would spell the end of this festival, honestly. If we continue to have repeats, it ceases to be special. Sure, the core group (this forum) would support it in just about every form, but the ticket-buying public would be hard pressed to see 12 bands they've already seen before at a festival in Georgia.