> Currently Lightning is somewhere around 15% of our total bitcoin payments. This is very much not nothing, and all of us here want Lightning to grow, but I think it warrants a serious discussion on whether we want Lightning adoption to go to 100% by means of disabling on-chain commerce.

Is this about disabling "on-chain instant commerce"?

 - Waiting for confirmation on-chain before shipping a product won't change, normally it's 15 minutes or so.  This doesn't change that.

 - An easy way to cancel/rbf a transaction doesn't exist - like you said, there's no UX for this now, and I don't anticipate one being broadly used except by inter-exchange transfers, etc.

So what does this change?

 - In the rare event that an RBF transaction is received where the fee level means confirmation times will be slow a merchant will have to wait very long for at least 1 confirmation, the merchant should alert the user that the transaction may take longer than the BTC FX rate guarantee window, and may require additional funds if FX rates change.

 - Users with wallets that support RBF can now be encouraged to accelerate the tx, with help and advice depending on their wallet, in order to lock in the FX rates

 - 0 conf is still viable strategy for releasing an order, as long as fees are very high, and it's very likely to be included in the next block.   More fee analysis is needed to validate 0 conf and mitigate risks, but now it is, at least, more "honest" to the true risks.