MadWorld will definitely outsell No More Heroes. It actually has commercials. It's advertising with contests and prizes. It's getting better review scores (for the chumps who factor that into their purchasing decisions). The Wii userbase is bigger, and hopefully fans of No More Heroes will be into this game after hearing all the comparisons. It also has media watchdogs whining about Nintendo forsaking its "kid-friendly image," which can hopefully generate some more hype and sales.
I want this game to outsell NMH, and then I want NMH2 to get really crazy awesome to retaliate. While I really like MadWorld, NMH is the one that I want to become a successful franchise. Suda51 doesn't have an all-star team like Platinum does.