The greatest French hackers like Jean-loup Gailly (zlib) and Fabrice Bellard (ffmpeg, QEmu and much more) actually went to Polytechnique (X), where they actually got something 42 students are very unlikely to get, an extremely strong math background readily applicable to multiple fields. Fabrice Bellard was already an excellent self taught programmer at age 17 when he released LZEXE. What got him to superhero level was likely more the well rounded, traditional French generalist engineering coursework he followed at X.
I completely fail to see what would attract such bright people to the 42 school, when X, ENS and a few good engineering schools and university programs are available.
42 is an excellent opportunity for the people that for some reasons didn't strive in the more traditional system, but I find the possibility it start to attract top people very remote, because being taught by students two years older than you isn't nearly as attractive as being taught by top researchers, and being on a campus and mingle with top mathematicians, physicists, biologists chemist is IMHO a lot more stimulating than being among only rejected by the system computer geeks.