First off, the source. An interview from Eorzeapedia in early March:
Q. You previously stated that: “significant changes to the battle system are necessary to create a style of combat that lends itself to the enjoyment of quests and miniquests.” What did you mean by that? What changes to the battle system are we in store for?
A. The current system, which contemplates fifteen-person parties, is very difficult to balance, especially with the current class system. The first fundamental change for Yoshida-san is to reduce this target party size to 8, although he also wants to allow parties as small as 4 to be fully functional.
Yoshida-san admits that currently the role of each class is very vague, and that one of the major initiatives is to make each class unique. According to Yoshida-san, each class should have an identity of its own – including a specific and defined role in the party. The changes related to this initiative will lead to tactics in a battle setting – which Yoshida-san made clear was one of his ultimate goals.
Related, but as an aside, Sundi added that the current trend in the MMO genre is for smaller parties, but also smaller linkshells/guilds. In other words, a move away from the 200+ person linkshells/guilds, and a move towards smaller, 10 person linkshells/guilds. FFXIV intends to follow, and support, this trend.
This thread could easily just need a clarification, because it wouldn't surprise me if eorzeapedia exaggerated this. Just in case though I'd like to bring it up and discuss it.
Now I'm not really sure what this trend is they are talking about. I have yet to be in a linkshell/guild in any game, especially a endgame LS/guild that had less than 30 members. In fact the smallest endgame LS/guild I've ever seen was 17 people, all were very active, and that size LS is rather uncommon.
I personally am 100% against such a drastic decrease. A LS around 10 people wouldn't even be enough for me and all of my friends, let alone my friends friends. I prefer LS's with at least 25-30 active members, with at least 15 very active members, and I would like content to support such members.
I think reduction of party size is one thing, but a reduction in LS size would not be well liked by many. This is a MASSIVE multi-player game. Let us be social with as many people as we want.
Also lol@200+ person LS's. Who does that?