With all the reported leaks, very strongly feel 4680 will be in the Plaids. If they are ready for Austin and Berlin to start Y based production in a few months... Why would they not be used already in low volume products?
Plaid is also reported to deliver peak power from 0, all the way to the top speed. IMHO, that's something could not be possible if it was the 18650.
S/X will continue to use the 18650s, there's no reason to give away a big chunk of cell capacity when being battery constrained.
BD was over 9 months ago, and it was mentioned Tesla was running cars with 4680s back then even. I personally don't expect much on the range front, maybe round out to 420, or go full memelord at 469 - but, showing the world that 4680s are now shipping in cars, beginning with the most expensive cars they make is the most bullish news one could wish for.