The way it worked in FFXI and a number of other games, is that many instanced fights are done in the same field, but just set farther apart so you don't actually interact with other people in that field.

So I think it may be more likely that they're just talking about making it so that there is a population cap on the fields so that a larger number are used, possibly using more of the servers they're implementing, so as to avoid server hiccups.