I also wonder how the move to IPv6 will also affect the current paradigm. Internet facing firewalls were typically also NAT machines to save IPv4 address space but all of that is gone in IPv6 meaning your global address is now exposed and a hacker can persistently try to compromise your machine if you don't firewall.
On top of that many modern defenses are based on IP reputation, or black lists. There are several companies that track the reputation of all 4 billion IPv4 addresses. Scores are updated every 5 minutes. With several quadrillion IPv6 addresses this will be a lot harder to do.
