Nothing wrong with keeping a sport and luxury model, however I would argue that the latest models are quite sporty and luxurious in their own right.
Companies like Ford constantly discontinue models, but they don't get the level of attention Tesla does.
If Tesla aren't seeing the Model S and X being sold to anywhere near the degree of the 3 and the Y, then why continue making them? They aren't as globally available and its clear people don't want them as much as the others.