The problem with your conclusion is that you seem to be assuming that Congress can do anything to put someone in jail. They can't. They can hold their hearings, and they can ask the Justice Department to prosecute, but there is nothing they can do directly. They can't even enforce their own Contempt of Congress orders - they have to ask the Justice Department to do so.
They only power Congress has to impose their will is the Power of the Purse. In order to force cooperation and compliance, they could refuse to appropriate money to the the departments that are refusing to cooperate - in this case, the IRS and Justice. However, both Boehner and McConnell have made it abundantly clear that they will never "shut down the government" again. So all Reid has to do is refuse to vote on any appropriations bill that reduces money to these departments, and then wait for the House to cave when the government "runs out of money" because of the mean GOP "holding poor Americans hostage for partisan purposes."
The GOP has already surrendered the only weapon the Constitution gave them - so all of this is just for show, and you can tell by demeanor of the people testifying that they know there is nothing that Congress can or will do to them...
So there's only one thing the HOR could do, since they traitored us on using the power of the purse. That would be research....computer forensics to find those emails, anything from another source that includes the contents of the emails, detective work.
Otherwise, there's no point in the hearings. People don't respect talk. They would respect action.