If you will notice bustr, that HTC actually had the dynamic instancing idea *before* competitors, before the tank one, even.
Remember "tour of duty"? (even free h2h arenas provided a level of that, just not automated).
HTC, as long as it keeps one large, paid, persistant arena will always keep to its design agenda. That's one thing other competitors don't have yet, because they were not designed that way from the ground up.