I must say, Mylord, that your thread is of better taste than the one sported by the boy who lived... Firstly, I have to admit that if I don't necessarily agree with all your means to attain your ends, but I still admire you for your dedication, perseverence, skill and ambition. As Ollivander has said in the beginning of the books relating your (mis)adventures, you were destined, after all, to do great things...
Purety of magical blood is not without reminding me of European Royalty. Princes have gone to great extent to avoid mingling common blood within their lines, as you might have learned in a muggle school before Hogwarts. They married amongst each other, cousin with cousin, much like the pureblood magical families, and have suffered through it with a considerably frailer health and generally smaller life expectancy. I do not neglect the possibility that magical blood might allow, perhaps, for avoidance of congenital malformations, but is such not a risk, in a world ruled by pureblood supremacy?
I very much understand your motives and see how such an elitism might benefit the wizarding community, and perhaps, who knows, the world in its entirety. I am, myself, somewhat elitist, and I dislike all that is crude and vulgar. But in a practical sense, I seem to find it difficult for a world led by purebloods alone to truly prosper. For instance, there seems to be no control over where a magical being might be born. How then, would your government deal with the situation of muggleborn wizards? You yourself, as a youth, were very much aware of your powers, and even untutored by formal magical education, were capable of causing much harm if you so wished. If muggleborn magical beings were left without a proper magical education to control and use their powers, how would your government have any stay over them? Would muggleborns be allowed a certain, if lesser role in your society, in the hopes that they might one day have children with pureblood wizards, and their children have pureblood progeny in their turn?
Also, what about after the successful creation of this new order of things? Once a pureblood supremacy is established, and once a successful government is created and status is controlled, what next? Are muggles meant solely to exist to bow and serve the wizards with little more than a rank of animals? Or, are wizards to be as the lords of the past, wielder of power, but also protectors of their servants? After all, there can be no magical blood supremacy, if there is no muggleblood beneath it...