Had an interesting game of "What If" with some interesting folk. Based on a few key opinions: (1) It is not in Russia's best interest for Ukraine to be admitted to NATO, and because of that it is also in Russia's best interest for Ukraine to be unstable (politically); (2) It is not in Russia's interest to have MAD with the US; (3) Economically (Hayeakian), Russia has a strong advantage over the US currently and full on war might reverse that; (4) A world war composed of only 2 sides would probably disrupt the BRICS ascent towards a world reserve currency.
Afterwards, I came up with an alternative scenario (the first few happened before I wrote this):
Russia, US, & NATO trade threats while Russia continues to fortify it's territory and Crimea. Russia sets up make-shift diplomatic offices in the Donetsk and Luhansk areas, and give out Russian passports (and citizenship) to those they deem meet the qualifications. Russia allows the free (civilian) travel of those with Russian passports into and out of Donetsk & Luhansk from Russia. In a faster series of events, Donetsk & Luhansk declare independence. They sign a treaty with Russia, where: 1) Russia would recognize Donetsk & Luhansk a free republics, 2) Russia would sell humanitarian supplies, DEFENSIVE arms, and technology to Donetsk & Luhansk, 3) Donetsk & Luhansk would agree to use a currency that Russia would dictate, 4) Russia would allow the DPR & LRP to send troops into Russia for advanced training. Other countries like Belarus would then recognize Donetsk & Luhansk as republics.
Much gnashing of teeth from Europe, NATO, & the US. Russia starts building permanent military bases in Russia near the borders. Donetsk & Luhansk start building wall-like structures for the border with Ukraine. Building of embassies are announced. Allied countries continue to beet the drum that Russia is going to invade, but they do not. NATO moves military units into Ukraine, and Russia counters with a series of strong economic escalations: Reducing (but not cutting off) the sale of gas to Europe, but dramatically increase the price to net benefit Russia; continue to reduce exposure to the USD and the EURO, while announcing agreements to buy/sell goods in currencies that are friendly to Russia.
Eventually Ukraine will start attacking Donetsk & Luhansk either with full force, or with small attacks. As these escalate, and Russia does NOT respond by invading (but does offer more and more military support to Donetsk & Luhansk), other countries around the world, including China, South Africa, Brazil, and India recognize Donetsk & Luhansk as independent countries. (This could take years and while waiting...)
Russia's economic actions (and likely some "third party" hacking" of US infrastructure) push the economy in the US from deflation (in early 2022) into a reverse of very high inflation (over the next 3 years). At this time, the Federal Reserve starts decoupling the rise of interest rates from the price of interest on the treasury bonds by buying large number of them to keep the yield low, while increasing the interest rate to "fight inflation", effectively monetizing all the US debt as it comes up for renewal. Every country in the world stops rebuying the t-bonds because of the low rate, effectively leaving the Federal Reserve as the only buyer. This causes the USD that are all held internationally to start coming back to the US domestic economy, causing very high inflation.