I think Adobe might have soemhting to say about an interface that resembles PS so much.
As a concept it oculd have potential as a backup to help people but for a marketplace like this many people using graphics will be designers with access to Adobe.
With all due respect the reason noone really challenges PS is because of the sheer investment, extent and quality of the software - something which Gimp or an other tool have yet to come close. If you can get even half close to PS then you should be looking at much bigger opportunities in developing or licensing it.
good luck