Who's to say what could happen on that front? The context is a ten year span. Any new model / iteration could easily be designed and brought to market in a couple of years.
There could also be yet another business branch for Tesla, providing the resources to help others build factories using Tesla's proven strategy and licensed technology. A supervisory role where Tesla essentially provides Tech Support for factory design and construction, for a fee.
Sure, anything like that is possible, but that does not change the fact that castings with structural batteries cannot just be supplied by Tesla to other OEMs like they could with a skateboard, they will have to do a joint design which is harder and more time consuming.