Linux isn't going anywhere on servers at least. If anything, Linux's problem is that it's edging uncomfortably close to the point of being too big to fail, in many sectors.

But I can unfortunately concede your point with consumer devices. I've come to the conclusion that Android will be doing a quiet Linux->Fuschia switcharoo in the future (https://news.ycombinator.com/item?id=15506377), for example.