The Manhattan legacy

The Manhattan Project was the highly secret American atomic research study which led to the making of the atom bomb. What is not so well known is that before the Project, fluorine was a difficult and dangerous element, while afterwards it became a key ingredient in all the new inhalational anaesthetics. Prior to this, the only practical inhalational agents available apart from nitrous oxide, ethylene and cyclopropane, (and a few others of short-lived popularity like acetylene) were non-halogenated ethers and some chlorinated compounds such as chloroform and ethyl chloride. When chemists learnt how to handle fluorine, a whole new world opened up, first with the 'Freons' as used in refrigeration and then the halogenated anaesthetics. Along the way, many halogenated compounds other than ethers were tried but abandoned, and now we are left effectively with two halogenated ethers. Is this the end of the line for inhalational anaesthesia?