In these cases doesn't the value in "Wow, this is really useful." completely outweigh the cost of having to learn something else if it does go away? It's not like you have a finite set of things you can learn and then that's it, brain's full.

Just use it until it stops being awesome and then use something else. Life's too short and your time is too valuable to pass over things like this, where your gut feeling is probably correct.