Many state militias were called "National Guard" prior to being federalized.
Prior to WW2, the militias were "de-federalized" following each war they were federalized and we went back to a small standing federal military.
This didn't happen after WW2, due to the Cold War and having to keep forces in Europe and Asia to "contain" the Soviet Union.
However, this Wikipedia page has information of state militias that are NOT federalized: https://en.wikipedia.org/wiki/State_defense_force
Just pointing out the National Guard didn't replace the state militias.
Technically, they could still be de-federalized. Either by Presidential or State Governor order
But that would mean the state would no longer receive funding for the NG ... and no state is going to give up federal funding of any sort.