What shall happen?

[Googi]

Originally Posted by Triple_Darkness

Yet it was never given a true reason

Serious answer:

If Stefan dies, then Unixmad either hires a new programmer, tries to continue without Stefan, or just shuts Graal down.

With Unixmad, it depends on the business structure of Cyberjoueurs. If it's a corporation with a broad base of shareholders and Unixmad doesn't have a controlling share (which I highly doubt) then they would elect someone else to be in charge. If it's purely Unixmad's private property then it just passes to whoever his will specifies (there's even a strong possibility this could be Stefan?)