I suspect that with the rise of EVs, oil will be cheaper longer than 20 years. Some estimate that we have in between 50 and 250 years of oil left in the earth.
https://www.fool.com/investing/gener...-oil-left.aspx
BP estimated 53 years in 2013, but they were basing that only on proved reserves. In the 1980s, people predicted that we would run out of oil in 31 years. I'm sure that BPs estimate will also fall short; improved technology will allow us to harvest more oil from other sources.
I think VW is hasty in making the statement that in 2020 they will not be developing new ICE engines.