I wouldn't be surprised if the government tries to buy it all up, whether its a conspiracy to keep us away from it or not. Government is weird, especially when you're not involved in it. Expecting a government to make sense is like expecting the weather forecast to be right. Don't count on it. Also, just because something weird happens doesn't always mean its malicious. Sometimes it can just be a lack of communication between departments, or simply plain old stupidity.
As for what I DO see happening, I see plenty of 5.56x45 and civilian .223 available. Stores where I am are full of it, and you can get 1,000 rd lots of brass case green tip penetrator ammo on MidwayUSA for under $400. If anything that "penetrator" ammo is more available than ever. If the government is buying extra, factories will increase production to meet that need. There might be a short-term shortage, but why would companies pass up the chance to keep making profits on a lucrative civilian market? Where there is a dollar to be made, there will be somebody there to make that dollar.
However, the prices are rising. The lies I do know the government tells are the inflation numbers....