The current version of the militia is the United States Army National Guard and Air National Guard.
Which is contrary to Federal law and has never been the meaning of the term "militia".
A solution would be to create a new group similar to the civilian Marksman program. Run a background check and safety course on every able-bodied adult over 18. Have the government issue to them a sidearm and a rifle from our Surplus stores. Fund organized ranges and Supply ammunition for those who receive arms. One step further would be To officially name them as citizens militia.
Keep in mind that the Second Amendment protects the right of "the people" and not that of the "Militia".
It really doesn't matter much how you define Militia. It matters how you define "people".