You are correct that at this time the 2020 training/exams are the same as for 2019, all based on vSphere 6.7.
I would expect that to remain the same for as long as the software version doesn’t change.
So for the time being, it wouldn’t make a lot of sense for a VCP-DCV 2019 holder to do anything in relation to VCP-DV 2020.
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