They'd never do it unless he were caught in bed with a dead girl or a dead boy. The black vote is just too important to Democrat electoral prospects.
But even if they did impeach him, hey, impeachment is no big deal. Why, consider these two crooks:
The grinning dude on the left is Alcee Hastings, who now sits in the House of Representatives (representing Florida's 23rd District), after that same body impeached him 413-3 for bribery and perjury as a federal judge. And the guy on the right is Marion Barry, the second and fourth mayor of DC, having done a stint in the can in between mayoralties.
If this were anyone other than the Clintons, I'd agree with you. But this is about Hillary, not the democrats. Once she has her foot in the door as VP, all bets are off.
I don't think she has enough pull with the Secret Service to have them look the other way when she suggests a walk in Ft. Marcy Park, but I think she owns enough low level bureaucrats at Justice to have them find whatever evidence she needs to start impeachment proceedings in the House. Owning enough congresscritters to make impeachment happen is just a matter of owning FBI files, also available from the Justice Dept.
When the Republicans went after Clinton, they went in with the evidence available to them, and proceeded according to the law under the Constitution. When Hillary went after Nixon, she went around the law. She re-wrote the rules to forbid Nixon's having an attorney to defend him. And she was only a low-level staffer at the time. Imagine what she'd be able to do with the network she has in place now.