Frankly, I don't see why a future edition should be less valuable than this rare first edition. I'm not saying it won't be, but why should it be.
You mentioned art. Well, the art is in the written words, and perhaps some pictures that might accompany those words. The artistic value remains the same, no matter what edtion it is printed in. The high value of this object isn't a reflection of it's artistic value, but because of collector's supply-and-demand. It's valuable because lots of people want it, not because of the content within.
I say read it, and sell it, and if you can ever buy another edition of it, at a normal retail price, do that.