Meh.
Lots of other ways that merchants could arrange to pay transaction fees, I don't think we need a hard fork to solve that problem.
E.g. : child-pays-for-parent.
Or an extension to the payment protocol so the merchant provides an already-signed SIGHASH_SINGLE / SIGHASH_ANYONECANPAY input to pay the fee that the client includes as the first input in the transaction.