Thinking it for bit it comes to "what comes after Git" and what does "Git" mean there.

To build better tool than git, probably a few months by tiny team of good developers. Just thinking of problem and making what is needed... So either free time or few hundred thousand at max.

On other hand to replace GitHub. Endless millions will be spend... For some sort of probable gains? It might even make money in long run... But goal is probably to flip it.