[boxed]

> How do I handle my own credentials when I have no idea which way a coin toss is going to go when I reach the site?

You'll notice which one you got to after the redirect obviously. Reset credentials isn't a huge deal either, it happens after hacking attacks all the time.

> How are certs handled?

I don't understand this question. There are two different companies afterwards, with their own certs and their own name. No problem at all.

> What would anyone gain from one Google becoming two, identical and indistinguishable Googles?

Indistinguishable? No. They must rename. And they will diverge over time as they try to compete. You know.. like markets are supposed to work.