I would assume that trailer will come once the version is much closer to release. There's no sense in expending time, energy, and money on a trailer for a game that doesn't have an end in sight in terms of creation.
The OP was a little trailer in and of itself, and Hampa may send out some footage later on if he accomplishes something he's proud of or knows you all want to see.
More than trailers, to me, a nice dev blog or at least basic progress reports on the game would be super neat.