It's all a variation on the theme of propellers: a high-bypass engine is basically a ducted fan, which is nothing more than a propeller encased in a shroud at the end of the day.

It is, all engines have them (well most, there is experimental propless one), just that in most modern combustion engines they are encased. The revolution comes from the blade design, the counter rotating fans design which needs such precise calculations to work efficiently, that supercomputers are required and then there are new composite materials among other more incremental advancements. All of that will allow them to design blade-out modern engine which will have radical improvement to efficiency.