Well, our justice system is based on that being the default position, until proven otherwise.
I think that right now the evidence for obstruction of justice is weak. And there has been no evidence yet presented that he knew anything about collusion with the Russians.
But I think there's something in his psyche that leads him to be so loose with words and deeds that there's likely a smoking gun hidden somewhere. I hope that at some point one of his cronies hands him up as part of a plea deal or immunity deal. Flynn? Manafort? Someone else?* One's allegiance can be sorely tested when one realizes they've been thrown under the bus and could actually face jail time.
The Opening Arguments podcast has good insight into the process. They point out that investigations like this can drag on for years, and that Trump detractors may be best served by patience.
At the very least, it makes for good drama!
*I may be gullible and/or naive, but I thought Sessions was pretty sincere and honest in his testimony, right up until he played the "future Executive Privilege" gambit.