The Roadster's never going to become magically forward-compatible. Just like it's physically incompatible with superchargers, I'm sure it's physically incompatible with having its battery swapped.
Conversely, the X has a huge technology overlap with the S. So it's extremely likely that it will work compatibly.
As for licensing the tech to other manufacturers, Elon has already said he's willing to talk with other companies about making the superchargers available, although there's accounting to be worked out.
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The Roadster's never going to become magically forward-compatible. Just like it's physically incompatible with superchargers, I'm sure it's physically incompatible with having its battery swapped.
Conversely, the X has a huge technology overlap with the S. So it's extremely likely that it will work compatibly.
As for licensing the tech to other manufacturers, Elon has already said he's willing to talk with other companies about making the superchargers available, although there's accounting to be worked out.