No, it won't.
If anything the IRS is going to be making more money on Tax Evasion fines with the way people around here just choose to not report anything to them.
For small amounts, sure, you might get away with it, but if you are making tens of thousands of dollars "vanish" by hiding it this way, you're probably going to find out the hard way.
Remember, you gotta have Fiat to buy it first, and that Fiat is probably sitting in a bank somewhere.
Good luck to all of you who choose to try to do this and think you're pulling one over on them. The same thing happened with offshore accounts. They found a way, and they nailed people to the wall who did it.
Except more people will work for bitcoins then will be buying from centralized exchanges in the future. The collapse of centralized exchanges will be the beginning of a bitcoin economy.
Can't wait for all these exchanges with their bad support and policies to get booted out by decentralized ones.