I wonder if people will ever stop bringing that article up...
v6 provides lots of ways to coexist with v4. There's dual stack, Teredo, 6to4, 6rd, 6over4, ISATAP, 6in4/4in6, NAT64/DNS64, 464xlat, DS-lite, MAP-T/E, 4rd, LW4over6... how can you argue it doesn't?
Facts are these: IPv6 is a failure; it didn’t provide a way to conexist with IPv4 [1] and it did _not_ have a _compelling_ benefit to most people. The benefits cited makes no difference to most.
[1] https://cr.yp.to/djbdns/ipv6mess.html