Of course. That's great for hints and private data too, but if we do extensions with the values nested under the namespace, we might as well forget about making them part of the core spec because migration day will break everything.
It will break anyway if we have to change the name of the key.
I put it to you that for any tool that is using the experimental key, the day that we move to the core is one day the authors of those tools will be very active, and quite capable of adding the few lines of code needed to handle it.
Adam K
