Today, yeah. But what about 10 years down the line, with an India worth $10T and a China worth $30T, and both interested in diversifying away from USD? China is definitely going to push for using yuan, could very well start in just a few years. India will eventually push for the rupee.
The dollar's worth is based on how much demand is there for it in the international market. Right now they do not have a real competitor. Not so in the future.
So China buys oil from Russia? And that's enough? What if Russia decides to stop supplying oil and gas to China? How soon do you think China can replace Russian oil? How desperate can Russia be to supply oil to China at the cost of their sovereignty?
Before the war, the Russians could balance their budget with $44 oil. With the new exchange rate, the Russians will be able to balance their budget with $29. Meaning if they sell at $90 over the course of the year, the Russians will be able to make a 3x surplus for oil. Which means they are earning the money needed to balance their budget with just 4 months of oil sales. Which means they can stop supply of oil to China for the remaining 8 months, enough to make China struggle to find a different supplier to make up for the deficit, but at a much higher price and a massive hit to their overall economy. Is that really a price China will pay to make Russia their "bitch"?
Energy suppliers always have the advantage. Why? They have the least to lose from disruption, especially so if prices are many times higher than the break even point. And the rise in prices will offset a lot of the losses later on.
Countries will simply find ways to buy Russian oil without using USD. No different from how Iran has been selling China its oil. They will find places willing to round-trip oil from Russia, like the UAE, Iran, Venezuela etc. Cheap energy in the Third World is a massive advantage to remain competitive.