I heard slight talk about the possibility of 10 man raids but was curious if there was information or any hints from the developers about having a 10 man option rather than strictly 20 man in the future (Greenscales Blight/River of Souls for example).

Many people from my old wow raiding guild decided to play rift together and we simply couldn't get more than 15 people, with the additional 3 or so people not being so reliable. With no server transfer options we couldn't find hardly anyone on our low population Guardian server able/willing to raid on Friday/Saturday.