Nixon was going to be impeached and removed from office. The House Judiciary Committee had already voted to impeach, so the motion to impeach was headed for the full House. He resigned because he knew he couldn't stop it.

It's true that he wasn't going to be imprisoned, but he wasn't going to "dodge the entire thing". I don't know whether he would have been prosecuted or not; Ford pardoned him before we got a chance to find out.