Here's the main thing with TSLA that makes them unique: vision and actually working towards that vision.
None of the legacy automakers have yet proven that they're working towards a strong EV vision, and until that happens, TSLA will be quite highly valued. And, while there are Chinese manufacturers like BYD that are visibly working towards an EV vision, they aren't doing things to near the extent of Tesla (and are focusing on transit and other fleet applications), and aren't positioned in the luxury space, so I don't see them taking TSLA's valuation down.
If a legacy automaker actually goes whole-hog into a Tesla-like infrastructure deployment (or, for that matter, piggybacks on Tesla's infrastructure), and actually converts a significant portion of their lineup to EVs that are legitimately desirable rather than being compliance cars, then TSLA's in trouble, at least in their current form as an automaker. They may have some competitive advantages in the energy industry, as well as with their US manufacturing of batteries and solar cells (in the midst of a protectionist policy era in the US), though.