I'm somewhere in-between "Intrigued; I'll take a look" and " Meh. Couldn't care less."
I was a Pathfinder fan and a *huge* Paizo fanboy for a long time, but the constant parade of new books really ruined PF for me. The game was always breakable, and option creep just shattered any pretense of balance.
I do want to see the rules first, as I have reservations.
But I really dig 5e, so it will be hard pulling me away from that edition. However, my players might really appreciate a game halfway between PF and 5e, with more building and character customization.
And I do have some PF adventures I would like to play through. I *might* put my 5e game on hold and run and updated Carrion Crown or Emerald Spire for a couple months.
Okay… I say that I want to playtest, but I probably won't.
My players will likely only be halfway through the Tomb of Annihilation and have spent six months doing 5e/ fantasy. If we wanted to take a break, it would be to play FFG's Edge of the Empire or Star Trek Adventures. We won't be ready to hit the playtest during the small window of actually being able to test through play.
The playtest period isn't particularly long. It's a year between the playtest book being released and the final book coming out, but with layout, printing, shipping and the like they'll need to lock in the rules by January or February. Previous PFRPG hardcover playtests for GenCon releases have wrapped up in December. And having seen narrow playtest times and hard deadlines result Mythic Adventures and the Advanced Class Guide, I'm a little wary with what will happen with a full ruleset and twelve classes.
They're saying Starfinder tested a few of the new mechanics… but that was pretty heavily 3e. Star Wars Saga went farther in terms of innovation and changing the game than Starfinder (and that game predated Pathfinder. And having seen some of the teased changes in Pathfinder Unchained, I want to see if they've been improved. (The three action system in particular was problematic and much slower than Standard/Move/Swift.)
Having bought 3e, and 3.5e, and Pathfinder, and Starfinder, and Star Wars Saga, and Midnight, and Iron Heroes I've bought a heck of a lot of variations on d20. I have that ruleset. I have it in spades. I don't really need it again.
Pathfinder 2nd Edition really needs to get away from the baseline math and rules of 3e and remake the game. Actually rebuild and fix 3e rather than just building yet another game on old, shaky foundation.