> I would like to structure this so that all shareholders have a choice. Either they can stay investors in a private Tesla or they can be bought out at $420 per share[...] My hope is for all shareholders to remain
There is also the possibility that your broker won't do the necessary paperwork and will just liquidate your position, or require you to move your shares to a legal entity that can assist you. Granted, they probably wouldn't do this without notifying you. And if you're a non-US person, there are probably issues regarding transfer of shares, potential tax realization and so on. Not to mention the requirement to be an accredited investor, which I'm not sure how Tesla will skirt. There are a lot of open details here.
I can see that my initial comment could be misinterpreted, but my point was that "You will be able to continue to hold" is not quite the complete picture.