Amanda - how does Unbounce fit into the goal of using responsive design? Can you share a bit more about your experience with the platform? Seems inexpensive enough if it solves this problem or makes it easier to rectify
Samuel, I wouldn't hold my breath there on a migration path. I am 99.999% sure that even if responsive out-of-the-box Marketo landing pages are deployed, existing pages will not be easily migrated. Responsive is not a one-size-fits-all type of solution.
If I am mistaken, then that's a good thing if it can happen, but I can almost bet my last name on it not being possible.