Wow! Love the composition and the sounds. Listened several times.
I think you could do a lot more with this piece, and so I agree with your idea of creating a longer piece from this demo. In fact, I think the piece would benefit with some more alteration between the more acoustic piano-like parts and the more intense synth lead parts. The only way to do this would be to lengthen the piece. Here is a rough idea of what I'm talking about:
The first section of the song is perfect. Then the leads synths come in on what I'd call the second section and pick up the intensity nicely. Then you return to a calmer section of the piano type of sounds, which is different than the opening, and provides a nice contrast/change of pace. It's excellent, too. Then in the last third of the song or so the the lead synths come back in and up the intensity, and the complexity of the arrangement increases. This third section is very good too, but this is where I feel the piece could benefit from some more slower suspenseful development. It's all good, but I think could be better with a little slower development.
If I had created this piece of music, I'd be really excited about what I had just created, and also excited about the possibilities. So I wish you luck if you choose to take it further.