Man, this is the second time in all 8 years I've got goose bumps while listening to a track. Insanely beautiful!
Okay, wiped away tears of joy and back to business: I think every element it needs is already there. It's all a question of arrangement now. From the sound you could give the arpeggios a little bit more room, so that they come into their own.
You have an almost perfect base here, when you have finished I see the track in good company to this 5 years old Audiotool masterpiece