Hotelling's law and Nash equilibrium can partially explain why so many "next silicon valleys" haven't panned out. It's also interesting that the valley is in a jurisdiction with such pro-employee laws.
For the purposes of having the next Silicon Valley, I'd wager the salient factor is pro-competition laws (such as California's ban on noncompetes), not pro-employee laws. It's virtually guaranteed that if California adopted French labor laws -- which are at least nominally very pro-employee -- and made hiring and firing burdensome, Silicon Valley will stagnate and many of those companies will go elsewhere.
Wouldn't Hotelling's law just predict that wannabe-SVs would try to copy every aspect of the original SV? I don't see how that alone explains their failure.
I'd attribute the difficulty of creating the next SV partially to capital/talent concentration being a coordination game (https://en.wikipedia.org/wiki/Coordination_game) - for any individual small developer, entrepreneur or investor, it makes sense to go where they have the best chances to thrive.