The Tesla Model 3 revealed in final prototype form in Musk tweet
What that means, if you're not familiar with software development lingo, is that the car you see is pretty much representative of the finalized shape and features of the production car. (You can think of the release candidate as the final prototype step, which comes after beta versions.) That means that Tesla almost certainly won't make any major styling or content revisions between now and the car going into full production.
With one exception. Just like in software testing, Tesla could discover some sort of "bug" that requires a fix. It'd likely be relatively minor – think of things like brake or steering calibration rather than a complete reworking of the interior. Meanwhile the car's software, of which there is a lot, is likely being developed and refined in parallel. So while this is what the final product should look like, it's probably not up to the standards of cars that will be publicly released.
Missing a problem that requires a restyling, for example, would be a pretty big failure of the development process up to this point. But it's not like it hasn't happened to more experienced players. Back in 2000, Audi offered a fix to TT Coupes after several had suffered a string of serious high-speed crashes, fitting a spoiler as part of a recall program, as The New York Times reported back then. That's an extreme example of an unlikely situation, but there's precedent.
Let's assume that with 17 years of computer advancement since then, and the importance of the Model 3 to Tesla's future, that sort of scenario has been exhaustively tested in simulation. If that's the case, the next step is to test this version extensively so see if any final issues crop up, and then "freeze" (we're using this term a bit loosely, since Tesla is famous for continual rolling patches and upgrades) the design to get the manufacturing process finalized.
This also comes on the heels of, and may be a response to, Tesla being knocked by investors for not having a beta car on the road already earlier this month. The company seems to be running a bit behind if it wants to start producing cars in July, but Tesla's also known for not hitting deadlines. While this but of Twitter PR shows progress towards that goal, we wouldn't recommend betting your nest egg on the Model 3 hitting the target date.
