If you're still interested in developing this song (which I would love to hear), I have a bit of c&c for you. Although if you're done with it, ignore me.
The first thing I notice is that the song is simply a loop of the same chord progression. Of course, going beyond that would mean you'll have to do some original composing and make the song "your own." However, it would most certainly be well worth it (besides, you already have original arrangement in here, anyway). In my opinion, 1:01 screams for a new chord progression, but you can do it anywhere.
You can also change the order of which the notes are played in each chord. Every piece of the chord progression scales upwards. You can try switching it up by, for example, having every second chord scale downwards.
The rhythm in the melody has been simplified from its original form. There's nothing wrong with this, really. I mean, I like how it sounds... But if you're going to change the rhythm, it might be a good idea to change it into something more unique rather than something more basic. Actually, it would be interesting to keep the melody's rhythm the way it is now, but when you re-introduce the melody for a second time, that's when you make the rhythm more unique.
All in all, I love how this sounds. You have a wonderful mood being portrayed here, and a wonderful choice of instruments doing so. I hope this post inspires you to bring it even further!