As much as I love the BF series, I find thier infantry combat to have always been utter crap (though BF2 is a lot better in this regard). The point to the series has always been its use of vehicles, and thier paper/rock/scissors gameplay they offer. Unless they're making changes to th mechanics and feel of infantry combat, an expansion focusing pretty much solely on infantry combat sounds like a bad idea.
But then again, I am a bit biased (Q3, RtCW, ET, etc.) as to just what infantry combat should feel like, coming from years of competing in games that used the old Quake engine (Q3A, RtCW, ET, CoD, etc.) - so I'm probably the odd man out on this one, and most others will have a great tme playing it.
Does anyone else find it odd that they're adding almost as many new armies as they are maps, you'll be playing a different army for each map for the most part, and there's no room at all for the old armies. Kind of strange.