This will be interesting.
On one hand, he has broken the rules so many times. Regardless of what your opinion are of pot, he's blatantly disrespecting the commission and he clearly doesn't care about the consequences. I think the commission cares less about the rules you're breaking and more about making a mockery of them. I can easily see them dropping the hammer.
On the flip side, if they gave him a long suspension for pot, the PR alone would be a nightmare. The headlines would read "Diaz suspended 2 years for marijuana". If casuals saw that headline and weren't aware of Nick's past, multiple failures and blatant disregard for the rules, they'd think it's complete bullshit a MMA fighter was suspended for that long over marijuana- "How is that fair? The guy was just smoking pot, he doesn't deserved to be suspended that long." So, maybe the commission doesn't want negative press over something that isn't a big deal.
So, I can see the commission either suspending him for 2-3 years OR only suspending him for 9 months, basically times served.
Who knows what route they'll take.