This is what has been termed as the 'Lost Book of Jules Verne'. The reason it was lost (and nobody actually knew that it existed until it was discovered in a safe in his old house in Paris) is because when he wrote it his publisher basically thought that it was rubbish and refused to publish it. So, like many writers, he simply filed it away for another time, and it was subsequently forgotten, only to be discovered in the late 20th Century. Is it Jules Verne? Well, it is difficult to tell since the version I read is a translation, and it isn't a 'travel narrative' as most of his other books are. However there still seems to be a number of qualities that suggest that it is.
One of the main questions though, is it possible that a modern author wrote it under his name and backdated it? Well, it is always possible, but what one needs to do is to consider what he was writing and the predictions that he made. The book paints a picture of a highly industrialised world, but we don't have concepts of flight nor do we have extensive use of automobiles (other than the Gas Cabs) nor do we have complex computing systems. We do have automated calculators and fax machines, but they were already in existence at the time, albeit in a basic form.
However, it is not the inventions that Verne is trying to paint here, but rather a culture. Sure he describes an extensive canal network that turns Paris into a Seaport, and he also describes huge ships which are pretty much floating islands, however the main context of the book is the social structure of the time. Basically, the story is about a young man who has just completed university, majoring in Latin Verse. However, it is pretty much a dead subject. The only reason he graduated at the top of his class is because he was the only person in the class. Much of the book involves discussions between Michal, his uncle, and one of his professors, who is a professor in Rhetoric, another 'dead' subject.
It is these discussions that actually show Verne's foresight into the modern culture. Art is no longer art and poetry is of no interest to anybody. While this may not be the case, people of the 21st Century have basically lost interest in the literature of previous centuries. Hollywood is pretty much a cookie factory that churns out formulaic movies, and when they do work on something from the past, they tend to heavily modernise it. While people still read books, many of the books that are found on the bookshelves, and what people read on the bus, are what my English teacher termed as Airport Trash. They are mindless books which people read because they don't really want to think about what they are reading. Further, many have turned away from reading and simply rely on television to the point that some will proudly say that they have never read a book in their life.
Verne's Paris is not necessarily like the Paris of today, and the French still seem to put pride in their movies, however it is difficult to say whether they still read books (I was only in Paris for 2 days, though they seem to), nor can I tell whether it is just pulp that they are reading (I can't speak or read French - yet). While the technical manuals that Verne prophesies as being the only books read in his future, and to an extent this is true of today (since the only books many people read are technical manuals, if they chose to read it as opposed to simply putting the items together as is).