It is a good technique. It was used in older days without a formal name - could be a group of folks going out for a beer one evening. This technique is more focused, and is generally done only by a narrow group of experts. Examples would be to identify ranges of operational speed for commercial aircrafts in the next 20 years. In general, a new technology replaces an old one about the time the old one runs out of steam.
Supersonic aircraft replace some jets for long distance travel.
This is an area where science fiction discussions can really help identify options for consideration. This is where one person interviews one person. This is a bit like the focus group, because you can keep asking questions until you get a satisfactory response. These are expensive and hard to do well, so there are not a lot of them. But, they are very good sources of information.