I agree. I think the stock will go up prior to the event due to anticipation and that we will go into March 31 higher than the ~$207 price we see today. However, this anticipation causing the run up in SP causes immense expectations and, like you said, I don't think Tesla can meet all of those expectations. Elon even said in the Q4 CC that they're not sure whether to show all of their cards (whatever that means - I'm still 99.99% certain they're showing a prototype and not just pictures.)
Just like the latest X reveal, Tesla scheduled the reveal at the very very end of the quarter, most likely to meet their own deadlines for the public. This tells me that they could be scrambling to get everything together on time. Also, to most people, Elon is not a great presenter. The general reaction to the X event last September was that they need a new speaker because the overall presentation was sub-par. I disagree with the fact that somebody else should speak just because I love hearing him talk and think it would be a shame for anybody else to present for the majority (JB would be acceptable, but still not the same.) I recognize that Elon's stuttering is just a result of him not memorizing speeches, but rather speaking as an engineer from the top of his head and in a truthful, non-deceiving manner. Even more people will watch the M3 event than the MX event, which will mean more people watching who are unfamiliar with Elon and his mannerisms, which will result in more people scratching their head and questioning the presentation as a whole.
So yes, I expect the stock price to fall the week after the reveal, but not by a substantial amount. There are some possibilities that could cause the stock price to rise even further immediately following the event, such as: If TSLA performs poorly during the second half of March and falls below 180-200 prior to the unveiling, if the stores are absolutely packed with mass amounts of people on the first day of reservations and those images go viral, or if Tesla knocks the presentation out of the park by doing something unexpected (like show a sedan and crossover model or if they have the car drive itself onto the stage.) Either way, the M3 is Tesla's version of the iPhone and will eventually propel the stock to all-time highs, so however the stock performs in the weeks/months after the reveal is relatively meaningless.