What are you talking about? Oil capital assets have regularly been abandoned (https://www.bcg.com/publications/2015/upstream-oil-gas-energy-environment-asset-abandonment-in-upstream-oil-a-growing-threat-to-the-sector) and/or stranded since well before 2020 (in fact, the big upswing started around 2012-2015). This is just an acknowledgement that this long term trend is really happening over the long term, and that COVID-19 has supercharged it (both temporarily and permanently).
There's a lot of reasons for oil to slowly contract both now and over the next 30+ years. Renewables are really taking off (and more importantly oil was never a particularly great fuel source, being beat out handily by natural gas in the electrical sector). High capacity batteries allow utilities to store peaking power instead of running inefficient oil peaking plants. Transportation is changing, and during COVID-19 there's a lot less of it going on. Governments and individuals are broadly becoming more anti-oil due to issues like climate change and plastic pollution. etc. etc.
COVID-19 and its aftermath will also cause some permanent changes. Even if most people return to work at offices, the infrastructure for working from home is much better established now, and it's far more ingrained as an option in our social consciousness. Companies will use WFH as a benefit to attract and retain workers, as a way to attract remote workers that otherwise wouldn't work for them due to their location, and as a way to straight up not have to pay for office space (or if they do, have a smaller office just for meetings). While I am WFH I am using a fraction of the gasoline I did when I was commuting to the office every day.
Keep in mind that the prediction was for a major long-term downward trend even before COVID-19 happened. It wasn't dependent on COVID-19 to cause a shift, the shift was ongoing long before COVID-19.
There's also the fact that coal has already fallen. Here's some recent stories on Slashdot about how far coal has fallen: https://news.slashdot.org/stor... https://hardware.slashdot.org/... The long decline of coal is a great case study in how this can happen, and while the case of oil is not exactly the same there are strong parallels as well. Just because we've been dependent on (insert resource here) for a long time and still have significant dependencies on it doesn't mean it won't decline dramatically and predictably in just a few decades.
The writing is on the wall, and even the oil companies and investors see it. They are preparing for the long slow decline of oil.
One more important thing to note is that a lot of the trends that are bringing down oil are still in their early adopter/early mass adoption phases, so this effect will just get more and more pronounced as we get further along.
For instance, EVs currently make up a little less than 2% of the car market today, but EV adoption growing exponentially and there are many reasons why EVs will replace internal combustion vehicles. They're simply a better product along many dimensions (power, silence, lack of chemical exhaust, durability/safety), they have far lower maintenance and fuel costs, you don't need to go to a gas station except on travel, all the major manufacturers are getting in on the EV game as they're afraid of being left behind, etc. A modern EV is good enough for most people most of the time and the TCO of the cheaper models is now on par with a typical ICE vehicle (more up-front cost for the EV vs more ongoing cost for the ICE vehicle). At some point fairly soon, EVs are going to go from a rarity, to commonplace, to nigh universal. 25% new car market share could be as soon as 2025, at which point it'd only be a few more years before almost all new vehicles are EVs and another 15-20 years after that before ICE vehicles are a rarity on the road, similar to how we see classic cars today. This could always take a few more years, but the long term trendlines are pretty clear.
The abandonment of ICE vehicles and uptake of EVs will also be sped up by the collapse of the gasoline distribution network as ICE vehicles become rarer. Gasoline is a volatile fuel, so you can't stockpile it, and so it won't make economic sense to keep small, unprofitable stations running. During COVID-19, gas stations are being helped out by an expectation of a return to normalcy soon-ish and by the fact that the producers need to keep the supply side open as much as possible so they can ramp back up more effectively, but in a long term decline unprofitable gas stations will just get shut down. Gas stations getting shut down makes it less convenient to own an ICE vehicle, leading to more people buying EVs, leading to more gas stations shutting down, a vicious cycle that will accelerate this trend.
If it's reasonable that the entire transportation fuel market could collapse in the next 30 years, taking 50%+ of oil demand with it, is it really all that radical to predict a 30% drop in oil demand? Really the only way oil isn't going to see at least a 30% drop in demand is if the whole EV thing just completely craters in the next few years.