The part I'm still confused is: how does the cache being updated? For example in the traditional web architecture if I go to www.example.com/index.htm, the host server of example.com tells the hash of index.htm and depending on that my web browser decides to use its cache or do a fresh request.
How would this work in IPFS? How about dynamic pages? Does that mean my browser still has to contact www.example.com to get the latest version's hash but then has the option to request the file from IPFS instead of www.example.com? What about if example.com goes down?
In basic ipfs the address is content-dependent hash - same url should always return same content (excepting hash collisions which should be so rare and improbable as to never occur in practice).
So the short answer is that there's nothing to update: and url will return the same content (or no content if no one has it pinned anymore).
AFAIK the ipfs approach to this conundrum is a name/resolver system - which essentially adds indirection.
This is Thomas he'll always be Thomas. But for now, he's also class valedictorian. Some time in the future, Thomas will still be Thomas, but someone else might be class valedictorian.
How would this work in IPFS? How about dynamic pages? Does that mean my browser still has to contact www.example.com to get the latest version's hash but then has the option to request the file from IPFS instead of www.example.com? What about if example.com goes down?