I don't think that will ever happen, and if it did a "person" FSD license would need to cost at least twice as much. (And then people would want it to be transferable, which after a while then there would be so many licenses that Tesla would hardly ever sell another one.)
Since Tesla doesn't discount FSD, in theory if you add FSD to your car it increases the value by almost the same amount. So when you trade it in you get that value back to go towards your next Tesla.
The incentives are two fold:
- To get access to the additional features: Smart Summon, NOA, etc.
- To get it at the current price before it goes up. (You are getting a discount from the full price because it is not yet feature complete.)