Only when the feds don't have a use for them. The National Guard is officially a reserve component of the US Army. The feds supply all the equipment, arms, vehicles, etc. The feds pay the NG troops when on training. The officers hold US Army reserve commissions, and the US Army completely controls whether they are promoted.
A state can have a separate State Guard, like Texas does, but the state then has to pay all the bills for that State Guard.
Theodore Roosevelt's 1907 rewrite of the militia laws (National Guard Act) has some constitutional problems, and this is one of them. The Constitution says the States have the choosing of officers for the Militia.
Congress can prescribe the training and equipment of the Militia -- but the Constitution does not give the Congress power to control the training and equipping of the Militia, only "prescribe" equipment and training regimen.
There are other problems as well, having to do with the Congress's pretended power to authorize the President to deploy and use the Militia overseas, for example. Hamilton and Madison would have a big, fat problem with what Bush and Obama have done, sending Guard units to Europe and the Middle East while their home States of Arizona and Texas are being invaded from Mexico.