Let's start with the things we do actually know about the reveal of the Model 3. It will in fact be shown to the public for the first time in March, which coincides with the Geneva Show. And, despite the fact that Tesla does not usually participate (i.e., have a booth) at most auto shows, the local Tesla Motors Switzerland Gmbh will have a presence in Geneva this year. So, while that's all interesting and could lead some to believe we'll see the Model 3 there, I remain unconvinced. If we look at Tesla's history, then we see that the California automaker just loves to show off its fancy new electric toys at its Fremont facility. That's where the Model S (and variants), the Model X, and even the Powerwall were all shown to the public for the first time. Why would the Model 3 be any different? It won't.
Tesla's booth in Geneva will likely be a place for the company to promote sales of the Model S and X. The S did well, saleswise, in 2015, but before the $35,000 (or so) EV arrives in the middle of 2017, Tesla needs to keep the higher-end vehicles moving from stores to customer driveways.