All this talk about "card networks" is missing that payment networks aren't all that relevant on international trade and aren't what makes sanctions by the US so devastating. VISA/MasterCard aren't prevented from doing business in Russia by sanctions outside by of a few targeted industries or financial institutions and other Chinese and Indian payment networks aren't banned in the US.
It ultimately comes down to us being the biggest consumer market in the world by far, meaning most of the world profits from selling things to us, giving us an enormous advantage as nothing we import has any real strategic value and everything else is a buyers market. We're also still the second largest export market despite running a trade deficit with virtually every nation on earth. Obviously we pay in USD for imports and its the only payment we'll accept for exports, but the USD's dominance as a reserve currency is a natural consequence of us comprising 50% to 25% of the worlds wealth for the better part of a century and its only makes implementing sanctions slightly easier.
We can afford to cut entire industries of some nations out of our market and take the hit while almost no foreign actors of any real importance can survive it without becoming a shell of themselves. Its so far been practically un-survivable if the US sanctions also target third parties who might make up the difference. International trade large enough to make a difference on a nations balance sheet, especially energy, is easy to track and any "middle men" Russia puts between the US and itself isn't going to help them if we start threatening to slam the door in those middle men's faces. Its a simple cost/benefit analysis and the US wins practically every time.
Anyone who thinks otherwise wasn't paying any attention to what happened after Trump pulled out of the JCPOA and reinstated sanctions, and especially during the 2019/2020 escalation with Iran and tightening of the last screws. By 2019 India was importing as much oil from Iran as they were from Saudi Arabia, both tied for the second largest source behind Iraq. And most of that was payed for in currency other than dollars, Iran needed investment to bring production back up after the JCPOA was enacted and the Rial was worthless so they set up a system to pay with Rupees which could then be used for Indian imports, and India owed billions to them that had previously been frozen by sanctions which was payed back in Euros via turkey. They were about as insulated from the spooky scary petrodollar as you could be and had very significant investments in Iran
On top of that literally the entire world aside from Israel and the Gulf Arabs were against us on pulling out of JCPOA, sometimes hysterically so. Europe and Macron in particular threw a massive bitchfit and even went as far to develop a mechanism called INSTEX designed to circumvent sanctions by bartering goods without the involvement of any US institutions or USD in a way that hides the buyer/seller.
None of that prevented Indian oil refiners or the Indian goverment from dropping them completely when we threatened to implement a full scale shoah on any entities, even ones several times removed from the actual business, that were "tainted" by Iranian trade in our jurisdiction. Indian/Iran trade dropped from 15 billion to 2 billion, none of it oil, in the span of a year.
INSTEX was similarly a pathetic failure, it sat fully operational for over a year before anyone chanced using it and it later came out in a propaganda piece about how the Europeans are "finally standing up to the American bullies" that this sole transaction was medical supplies which weren't even targeted by sanctions, we had offered them medical supplies ourselves just months earlier. Its probably an even better example of how even nations that talk a big talk about US influence on the global economy cant even bring themselves to play by our game and retaliate in kind, because they know it wouldn't work on account of that trade imbalance mentioned above. INSTEX wasn't designed to fuck us over or take something from us, it was designed to allow companies to trade with Iran secretly so as not to effect trade with us. We're prepared to risk severing the connection between us, they aren't.
So maybe people can understand why I find it hilarious seeing all this pontification on the imminent collapse of US hegemony or the "petrodollar" because India entered a contract with Russian suppliers to for a total of three days of domestic consumption worth of crude to be traded over a period of several months. For reference India export/imports with Russia are something like 7 billion and 3 billion respectively, I'm sure they'll give up trade with the US this time, because it's not like Russia has much less to offer them compered to Iran and it's also not like they risk far more severe consequences seeing as how the entire western world is in unison on this.
If you think Russia will just shrug this off let me tell you: the truly consequential sanctions haven't even started yet.
So far aside from restricted airspace and minor hurdles of being kicked out of SWIFT its all been private sector decisions. We're not prepared yet to take the same steps with Russia that we did with Iran, it would be premature mostly because of Europe's dead end foreign policy with Russia and lack of foresight, but every step to divest from Russian energy brings that reality closer.