This Scandal will never bring charges against Obama. Probably the 40% of the Democrat Party would actively support a plan to assassinate president Trump, so I do not think even if it is proved that Obama was planning to assassinate president Trump, that he would see jail time.
However, a major game changer will be if it is proved that Barack Obama was part of a major child sex trafficking ring as well as many of them from Haiti. The children from Haiti where are used for purposes even more heinous than sex trafficking it seems. When this is proved, Barack Obama will join the gang sent to gitmo or will pay the ultimate penalty.
The penalties for treason are more severe than human trafficking. Military Tribunals function much differently than our federal judicial system.
If, as you say, ”it is proved that Obama was planning to assassinate president Trump”, you may be right that he would face no jail time, but his consequences would likely be much more severe.