New transaction templates can be added as needed. Within a few days, there will be plenty of GPU power that accepts and works on it. Network support will be thorough long before there’ll be enough clients who understand how to receive and interpret the new transaction.
I agree with the whitelisting, this allows the generators to be more discerning in what they accept or reject. That said, as soon as the template for a good BitDNS implementation is released, I’ll be sure to add it to my generators whitelist.