Speaking with PC Gamer at E3 last week, FFXIV's North American Online Producer Yasu Kurosawa, revealed that the upcoming MMO will definitely feature global servers, explaining that, "From the community perspective, one of the things that makes us unique is [having players from] different countries playing together. It's the uniqueness of Final Fantasy XI. We would like to have a similar experience that nobody else among other MMOs is having."
When we followed up with questions regarding how they'll ensure lag doesn't become a major issue, Senior Vice President Hiromichi Tanaka assured us that the game design takes into account the lag issues that might arise with a global server population, "The game system itself copes with all the lag so it doesn't matter which region the players are accessing the game from--it's not going to affect the user's gameplay experience."
Kurosawa chimed to further alleviate concerns, "Yeah, it will be fair to everyone. Lag is normally not so much the distance, it's the number of people in an area. Even if [everyone is] in Japan, some [areas of the game] will lag and it could be unfair, so as [Tanaka] was mentioning, we're making the system so it will be fair to everyone."
Later in the interview, Hiromichi confirmed that a single FFXIV server will house "tens of thousands" of registered players, and be able to handle "five or six thousand" people playing at a time--about the same as FFXI's server loads.