Looks very much like my initial maps before I process the terrain using Wilbur (while working in Photoshop). Are you planning to erode your mountains with a program such as Wilbur? Although it looks beautiful even without the processing, I'd advise you do it anyway, and blend the result with the original image at a 50% or somewhat lower opacity. (That's my rule of thumb with my images.)

A minimum two-year project? Wow. That's a much longer time frame than I usually invest in my maps. Is this for a novel or RPG?

The bottom line: looks fantastic!

Peter