> Nash's theorem is a mathematical theorem, and the proof is sound. It can't become less true over time. Nash proved the existence of the solution concept he d

> Nash's theorem is a mathematical theorem, and the proof is sound. It can't become less true over time. Nash proved the existence of the solution concept he defined. It is true that at least one Nash Equilibrium exists for all games (with every information structure). It is more subjective as to whether 'Nash Equilibria' are particularly useful or interesting to specific classes of games. Indeed, VN-M had already proposed a different solution concept that they proved existed in a narrower range of games (best response equilibria in 2 player 0 sum games). In games with asymmetric information structures, stricter equilibrium concepts than Nash Equilibrium are often used, because there are typically a large number of Nash Equilibria for any game. For example, Bayesian Nash Equilibrium and Perfect Bayesian Equilibrium restrict agents to forming beliefs in a 'Bayesian' manner, whilst the latter also restricts their actions to also be BNE in subgames off the equilibrium path of sequential games.