I don't think taking up the coin was long term planning on Marcone's part. More like a "short term" (a decade, two at most) loan he's hoping he can skate on, before the angel in his brain puts him in a mindlock. I imagine he's very aware it's only a matter of time. It would be a weird gap in the savvy that we saw in Even Hand for him to think otherwise.
The hubris of trying to lead The Fallen is Nicodemus' thing, and Marcone got front row seats to Suffering Engine Inc's maximum intensity of fucked up clownshow being executed on Ivy. That's probably not the kind of attempted initiation that builds delusions of security. I imagine it does impress the reality of the game Marcone was playing into him, and made him confront the power dynamics at hand.
Marcone is very cunning, willful, resourceful, and at this point, the accumulation of power was basically happening automatically for him (not that he was lax in cultivating it, ofc). He was seriously not someone to be screwed with. Harry may have eliminated a bloodline in a moment of pique later on in the story, but Marcone murdered his way to the top of an industry where there are a standard number of generations for particular transgressions (interestingly enough, Marcone's bloodline related wrath probably only went upwards in the family tree as well).
He could always be more powerful, but John was just about topped out on what could be meaningfully expressed as a vanilla mortal in supernatural contexts. I don't think he skimped out on a single Monoc package, and probably earned a discount or two by inventing a few. At least it was as much as he could bring to bear without getting bogged down in more obligations than it was worth in mortal politics (although Lara Raith seemed to have found a loophole or two).
He then got ripped out of a saferoom in the heart of his power, every advantage at hand. By someone with the same personality type, assorted magic powers, an omniscient spy demon, and as salt in the wound, ~2000 years of compounding interest completely obviating any structural power of Marcone's. Since criminals take bribes if they're big enough. All as a test run/bait for a real player.
Oh, and Nic's gang literally worships him instead of being a traitorous backstabbing pack of criminals that require constant managing. Just on a professional level, being out-disciplined by the eunuch guy. Ouch.
Marcone isn't a hero getting by on moral-gumption-made-physical-power and regular abuses of free will at a breathtaking scale. He's a ruthless strategist who tries to win in every possible outcome (and who regularly games free will). He was helpless before powers greater than himself, so he got better leverage. He's not just aware that things are coming to a head, he's playing an unclear role in helping them get there. Therefore gaining more specific leverage over who knows what apocalypse-y shenanigans.
The blast crater formerly known as Chicago, to start with. Now that there has been one blast crater, there will be polite inquiries into if there will be a second blast crater by the mortal powers that be. The taboo on large (read: torch and pitchfork risking) scale politics is probably on it's last legs. Now that there's power to be made in brokering, it's gonna get made. How convenient for Marcone, ever a man of lucky placement and timing.
In his ideal scenario he probably saves Amanda Beckitt, saves His People and the world from whatever's coming, comes out alive himself, becomes King of Greater America (whatever the hell that means), dunks Thorned Namshiel in a Vatican vending machine for a pop, and skips off into the sunset with his ill gotten magical powers as Harry Dresden, new loyal employee, admits how wrong he was the entire time. Which John will magnanimously wave away to begin a fruitful and long partnership.
More likely, he will begin sacrificing those items in reverse order and with rapidly increasing frequency as the nemfected Fallen cheats somehow, and the brainlock goes faster than expected. And we get to watch! He just lost the closest thing to his conscience, which I'm sure was also totally unrelated to the similarly habitually fortunate Fallen Angel whispering sweet nothings to his subconscious.
Or at least that's my read. I'm not sure if the story is actually Freudian, or if I'm just slipping.
