>
> Actually, and this is key, there _are_ reasons why deposits might not
> be able to use PaymentRequests.  Payments happen even when
> wallets/computers are offline.
>

I don't understand this point. It's the *sender* that is parsing the
PaymentRequest and following the instructions. By definition the sender
must be online. A computer that is switched off cannot sign a transaction
at all.


> If you have negotiated HD wallet details, you can use a new address
> every time, as mentioned.


Yes, and an extension to BIP 70 to allow for this (or stealth addresses or
whatever) has been discussed several times.

This thread started by proposing (I think) an expiry time for addresses.
BIP70 satisfies this use case, I think we all agree on that. Now for cases
where someone can't use BIP70 for whatever reason, or it's suboptimal,
absolutely we should design extensions to fix that.