This is a mix of the FOSS generation getting old, and the newers ones rather care about free beer than ideology, and guess what, people writing that free beer software apparently have bills to pay, and VC folks to keep happy.
I won't be around to validate this, however I am asserting GNU/Linux will not survive after everyone that was part of its genesis is long gone.
Something else will take over it, will still somehow support POSIX in some form, just like most UNIX workloads were eventually taken over by GNU/Linux