I think that you’re pushing that point to the breaking point. Are you assuming that someone is going to talk? This administration has more control over information than any in modern history. No leaks, and they don’t even talk to the media. Who is going to testify truthfully?
Everyone will say that Obama knew nothing of this. They might fire a minion, maybe even Emanuel, but Obama will stay in office.
If you want to impeach, you’d better have ironclad evidence, and you’d better be able to pull it off.