I would not be surprised if the reveal at the end of March is not an event, but just a press release of some sort. They've hinted at this being just the first sneak peek at the design rather than a full prototype reveal. Perhaps the launch event comes a few months later when they are ready to give more details.
On the other hand if they are going to start taking orders it would seem that they would have something more and perhaps we see the outside of the vehicle only and they keep the interior a secret. In any event, its pretty exciting to finally get some official information about the car from Tesla. I was growing tired of all the speculation and fake image leak discussions.
If it is an event, I would love to attend, and if not, I'll definitely be visiting a service center to place my deposit as soon as they are accepting them.