So that trailer might contain a HUGE spoiler.
Notice the dialogue at 0:40 in this trailer when you hear the robotic voice during the clip of Vader's helmet. In the US version, it was just "I will finish what you started". In this Japanese trailer, it's "I will fulfill our destiny. I will finish what you started". Why would it be "our" destiny unless it's Luke's voice speaking? It could very well be an echo of Vader's admonition to Luke and his prediction in Episode V about how Luke "must fulfill [Luke's] destiny and rule the galaxy as father and son".
This whole theory is bunk. It just doesn't make any sense seeing what we've actually seen from the trailers and the promotional stuff.
SPOILERS
I still think that Kylo is a Skywalker descendent and see's Vader as the "real" person and not Anakin Skywalker.