"JP" as in Japanese-speaking, or as in "closest server"? I can speak both, but will physically be in Japan for the foreseeable future.
We'll be on Ramuh for this weekend seeing as the 1.0 data transfer isn't until the second stage of phase 3 (yeah, what a mouthful). Once we have our original characters back we'll be situated on Durandal for the remainder of the beta tests and to launch.
We're going to be making a Free Company or Linkshell, depending on what kind of population we're looking at among other things (Neogaf member and all-round mugon type Darte will be making it). There seems to be a number of JGAF joining but I haven't got exact numbers. Nothing is set in stone as to what the function of the LS/FC will be as it really depends on how often we can get together - providing we can function in JST prime time (18:00 onwards) we should be well and banging.
As for other people joining us, if you're not able to join into normal events and such there'll always be other Japanese shells which operate outside of JST prime time and accommodate for a range play-times, these are usually night worker shells filled with taxi drivers, mothers and occasionally kyabakura/host types. I can invite people to other Japanese shells providing they can communicate unassisted.
[edit] As for population it's hard to say. I assume there'll always be the type of foreign player who'll be hell bent on playing with Japanese players regardless of time-zone incompatibility, so long as they can communicate well enough and steer clear from the awkward anime type lingo I'm all for a mixed server.
