If the purpose of the 2nd Amendment is to form a militia, then get rid of it. No militia has stood up to a modern military with only small firearms in nearly a hundred years. The trope of mountainmen scurrying about the Rockies to fight the government is a fantasy. To say the concept is outmoded is an understatement.
If the purpose of the 2nd Amendment is to simply allow civilians to own firearms, fine. But does anyone really think the Founding Fathers would have OK'd all weapons? Their concern at the time were muskets with an effective firing range of about a hundred yards, one round a minute, with very low accuracy. Today, an AR-15 basically accumulates enough force multipliers (mobility, range, firing rate, power) to contest an 18th century regiment singlehandedly.
People seem to forget that the 2nd Amendment has a relationship with technology -- the only Amendment of its kind. It should be the Amendment we return to most for second looks. Who knows what kind of weaponry we'll be talking about in the future.