China will likely to continue to support Tesla because China wants to become an exporter of EV. This is why they allowed TEsla into China without a local partner. China doesn't want their companies to be restricted when operating outside of their home market.
But it's easy to forget that China has almost no major brands sold in the developed world. It going to be interesting how China navigates their branding. The ability to make complex stuff is ubiquitous in the modern world. Making the right stuff and branding it successfully is uncommon and not not an area where China has experience.
You are probably correct about motivation but quite in error about branding. China has a number of globally known and distributed brands, although only a few of them have been major direct players in the US. A handful of examples are useful:
Haier- globally well known in air conditioning and appliances
Lenovo- formed from the ashes of IBM's PC businesses
Anker- my guess is that everyone on the board has at least one Anker product
BYD- maybe not a US household name but well known to US bus buyers and many car/bus buyers around the world. (of course non-US helps, since i do note that nobody is surprised by the BYD I drive frequently.)
Alibaba- pretty close to a household name in much of the world.
Then there are London Taxi, Volvo, MG, Rover all acquired brands, of course.
BTW, As for "...China wants to become an exporter of EV." They already are, with BYD busses and cars and some others too. As the world's largest EV producers they're pretty quickly growing the exports, following their global dominance in Solar Panels, among other things.
If you had said China strongly desired to have the reputation for excellence in EV's that Tesla already has I would have agreed without reservation.
It is indeed sad to have so many people still underestimating China.