I don't see them raising the behest cap now that behests is once every 30 minutes. Yeah LS's used to do prepatch behesting will have to adjust, but in my experience behest are better now with only 8 people. Before when doing behests i noticed on several occasions people that were just auto-following other people without contributing to the fight, but still gaining SP. More control and less zerg fest now in my experience.
If they were to allow several groups to form alliances for behest it kind of defeats the purpose of them at all, since they are quick 20 min "go there kill these NOW" type missions. Not difficult, strategic, organized party content.

I guess when dungeons comes behest will only be for random grouping anyway.