Speculation here, but Ronnie would NEVER be convicted of much...
SPOILERS
In show finale, upon being arrested for "the last 3 years":
- What do they have on him? Only the dropping of money to Corrine, and Vic's testimony
So in my opinion, he would only get convicted for obstruction of justice (the money bag), since it's stated it's Vic's (not even Ronnie's), so his only actual crime is delivering it. Nothing else. LITERALLY.
And as for Vic's testimony, it's his word (a cop killer) against Ronnie's (an accomplice after the fact) unless Shane's detailed confession/memoir resurfaces (not likely, Vic burned his copy, same for Ronnie, and Shane's is locked somewhere no one knows, and his threat of it showing up on IAD's doorstep if he died seems a bluff considering his limited friends and resources). And even then, it's the testimony of ANOTHER cop killer, one too dead to be cross examined (so most likely, INADMISSIBLE).
So without that, they only have Shane's suicide note, which 100% blames himself and Vic, not Ronnie's. Plus:
- Who had unaccounted cash and lawsuits up the butt? Shane and Vic, nor Ronnie (Kavanaugh said as much).
- Who just admitted to a catalog of crimes? Vic, not Ronnie.
- Which one is suspected/guilty of worse crimes? Vic (cop murder), not Ronnie (accessory after the fact). So it's not like they cut a deal with a devil to bring down Satan himself. They cut a deal with Satan that resulted in bringing down a minion for covering up Satan's crimes. The drug bust alone can't justify giving full immunity to a cop killer (Olivia stated as much that they could eventually bust that cartel without Vic's help).
So you can see how any defence attorney would have a field day tearing apart Mackey on the witness stand and trashing ICE in the press (giving full immunity to a cop killer). Heck if competent he would literally summon Olivia and her boss to the stand to tear them a new one for the deal they cut with Mackey.
Prosecutors would be pressured to spare ICE more embarrassment and cut a deal with Ronnie (they already were ready to do that with Lem, so it's in character).
I just don't see him going away for life without taking a LOT of people with him, people whom would have the juice and will to avoid that at Ronnie's sentence's expense.