Since there is already highly efficient event driven I/O and a context switch is bound to happen for applications that require major business logic in user space, I doubt there will be huge benefits for large server applications.

Maybe simplified versions work with this paradigm with significant performance gains, but I doubt that you could simply plug Varnish or nginx in and see much of an improvement.

There is still quite a complexity gap between e.g. interpreting firewall filter rules and a full blown web reverse proxy..