I think you just hit the nail on the head. I would agree that the majority, if not all of the species of cycads alive today, were not around 200 + million years ago. Things change over time. I think they call that evolution. Ferns predate cycads, but how many of the fern species today were around 300 million years ago, or whenever they started to be around? This doesn't mean that ferns didn't exist that many years ago, they have just changed over the years.
Its like a plant that was brought to people's attention in South Africa about 10 or so years ago. There was a colony of Encephalartos arenarius that only came from this huge farm and they are VERY blue, or silvery looking. They have been called "the true blue arenarius" and have gone for a lot of money, like a plant with an 8 inch round stem going for about $4500. Some offsets were taken from the plants and sent to the US and the people who have bought them have been growing them up to a now, coning sized plant. Some of the cones are coming out a different color than they are supposed to and look much like E. horridus cones. Since horridus is a very silvery looking plant, it would be logical that this colony of arenarius, at one time, naturally cross pollinated with horridus. The thing is that there are no horridus plants close enough for them to cross pollinate. It is speculated that at one time, these two species over lapped, but that could have been 1000s if not millions of years ago. So, we are seeing evolution all the time, and goes beyond us lowly, mear people, who feel we have to put everything into a species name.
Maybe, in some ways, both sides are right on this subject. Maybe none of the current species of cycads were around 100 million years ago, but it doesn't mean that cycads weren't around at that period of time. I know the people who are wanting to write this new paper are looking at their fossils and looking at the coning structures, and they think, somewhere there, they will find the true answers.
If you like old plants in general, cycads are facinating. It is said that the oldest living cycad species is the Lepidozamia hopei in Queensland Australia and a single stem will live to be 2500 years old. Since most cycads can produce offsets, and thus can become a cluster, over the years, it is not unlikely that there could be a cluster that was started from a seed 200,000 years ago, but no current stem would be the original stem. I am blessed to have been given a cluster of Dioon edule, which can live 1500 years for a single stem, and the largest stem is large enough to be 400 years old.
There is a palm called Serenoa repens, (which we call "palmettos" here in Florida) and outside Daytona, there is a plant that is estimated to be 150,000 years old. These plants put out underground stems that look like stolons, and will make a cluster over time. Well, there is a big circle of plants, and the circle is about 150 + feet around and DNA material was collected from those plants, and it was found that all the plants are the exact same plant. Over the centuries, the original plant produced new branches and then the older plants died, so the middle is bare and the circle of plants are the same plant and it continues to expand. I think that is just too cool!