For example, NameCheap' WhoisGuard service has an option to rotate the email address every 30 days. If I subscribe to a service like that, will I have to verify the randomly generated address every time it is rotated?
Right now, they only ask for confirmation once a year regardless of whether there has been any change of contact info. But OP makes it look like I'll have to verify my email address every time it changes, and one of the main features of WhoisGuard is that the email address in my whois changes all the time.
If I tell NameCheap/WhoisGuard to rotate my email every day (probably overkill, but it's possible), will I wake up every morning to find a new confirmation link in my inbox?
As far as I know, the address confirmations are for your real address details. Namecheap isn't asking you to confirm the whoisguard details, and presumably the new provisions will function the same way.
Those were basically a way to nudge name holders to ensure the details they provided were correct to minimise the chances to people lodging WHOIS inaccuracy complaints with registrars or directly with ICANN. See here: http://www.icann.org/en/resources/compliance/complaints/regi...
What's changed is that the Law Enforcement Agencies have pushed to make registrars be proactive in checking that any contact information is accurate rather than reactive in response to complaints. It's likely going to push up domain costs quite a bit. Here's what registrars on the 2013 RAA are required to do: http://www.icann.org/en/resources/registrars/raa/approved-wi...