I don't see how you take it that way. Experience with containers will be very valuable over the next decade, and anyone with experience will have an advantage over someone with no experience. There's not one binary moment where all of a sudden technology X is mature and stable. Docker has been around over 3 years, and the underlying technology many years before that. Although Docker is having trouble on the orchestration side, the container format is quite ubiquitous already, so I'd say it's highly unlikely that Docker will completely disappear in the medium term. Finally, it's not all or nothing, Docker solves a lot of problems today in certain configuration, you don't even necessary have to productionize anything as it's quite useful in purely dev scenarios. Even in a worst case scenario where Docker becomes completely irrelevant, you've learned something about what works and doesn't work with containers.
There's obviously a choice where you want to pick things up on the adoption curve, so maybe you're more conservative than me, but my underlying point is that it is possible to find a balance and you can still advance your skillset even if you pick something that doesn't necessarily stick around for the long haul.