I have a strong suspicion that there will be no further attempts to fine US citizens travelling to Cuba. The fines never had teeth to begin with, and were never upheld in court as the government always dropped them first out of fear the whole thing would be struck down.

Moreover, with the requirement for an advance OFAC license now eliminated, anyone blogging their trip for instance could easily argue they were there for "journalistic purposes" (bloggers have been previously upheld in court as journalists) permitted under the general license. A freelance journalist could quite easily be spending her time on tourist activities as part of a journalistic piece (blog post) on tourism in Cuba...