It’s a bit too soon to tell. Obviously there will be a desire by many to design for the lowest common denominator, but that’s probably SMS, and not really the direction to go in. More interesting will be those tools and platforms that target 1–2 rich platforms and really optimize for them.
It’ll be less about “responsive design”, which implies visual consideration, and more about “responsive service” — i.e. how do brands and services meet their customers’ needs quickly and with superior experience?