I do not see why, there is still a much higher ratio of DPS vs tanks and healers in this game. Surely there are plenty of other groups who want to fill such a spot, especially in DF as opposed to PF or statics. It is true some places prefer to go single tank or single healer but generally such places require a very good tank or very good healer and those are hard to come by in my experience. I get the feeling your talking about only PF and statics but in DF your queue times will still be very quick and are in high demand probably. Remember any changes made to group size also affects DF not only statics and PF, if anything DF queue times will get longer if increase party size for all classes involved.