If it isn’t as simple as “Barack Obama committed High Crimes in ordering the intelligence apparatus of the United States to try to damage Donald Trump’s campaign”, it won’t matter.
And, before someone pops in to say “Obama can’t be impeached”, that is incorrect.
The Senate has not one but two punishments available after a conviction. The first, removal from office, obvously doesn’t apply to Obama.
But the second, “disqualification from any office of trust or profit under the United States” could prevent Obama, for example, from being an ambassador or being appointed to the Supreme Court.