Strong positive catalyst would not be enormous number of gen 3 deposits, that is a statement from potential customers. What we need for TSLA is something like a driveable ready gen 3 beta prototype to assure investors that TSLA is worth what it currently is, otherwise I could imagine some more investors selling some more shares.
I keep seeing reference to the prototype and people wishing for an Alpha or a Beta or whatever... the car doesn't release until late 2017! They are not going to have Alphas until early 2017 and Betas until mid 2017... Please understand, a one off drivable engineering prototype is *not* an Alpha or Beta. It is a concept car that is driveable... I have never seen a car start with the actual production design (especially if the car isn't getting released for almost another 2 years!) from anyone, and especially not Tesla.
To clarify on terms:
Engineering Prototype - Depending on the manufacturer there may be more than one, but generally just one, that shows a concept. It may or may not be drivable. It may or may not have a fleshed out (even partially) interior. I think someone said that in the Model S prototype they had painted up cardboard for parts of the dash!!!
Mule - While not mentioned here, this is the logical next step most (and even Tesla) take which is to throw hardware that you intend to put in your final design into something else and test it out. We saw this more heavily with the Model X as they would mule up a Model S with weight on the top of the roof to simulate the top heavy part of the SUV.
Alpha - These start to show final *design intent*. They will make a mix of drivable and non-drivable cars which are design intent for various parts. A lot of companies will outsource this, It is unclear how much was outsourced for the Model X. It is unclear how much will need to be outsourced for the Model 3.
Beta - These are built with *production intent*. The purpose here is to be building the cars on your own equipment. You know what the car will look like and how it will go together, now it is a matter of making them go together with your own manufacturing equipement. Changes made to the design at this point would be strictly to enable that production capability. Which is an important distinction from the Alphas where the design is still somewhat open as you are still toying with some ideas.
To give some examples of what should have fallen into the different sequences using the Model X (note that while I don't know these to be true, it makes sense that they would have happened here).
Concept: Wings, Windshield, AWD, Fast car, steering wheel with the cool buttons.
Alpha: Nosecone change, Seat design (also likely the point where we lost the ability to fold the second row seats), Transplanting the current steering wheel, AP, AWD decisions, Initial performance figures and tweaks. Finalized that Doors would happen, and how windshield would come together.
Beta: Replace parts supplier for the doors. This is a great example of where something was finally pulled on the Betas, as they just couldn't get production manufacturing to happen and had to change the lift mechanics. The doors work the same in concept, the driving factor is different. Moving the seat manufacturing in house (This might have caused some minor materials changes as well depending).
The key things here is the amount of visible and utility changes to the cars that would have happened. So I said that all to say, that what we see in March is 99.99% likely to be a drivable engineering prototype. This is based on timing of when the car is expected to release and how Tesla has operated in the past with releases. If you are going to be disappointed that they aren't showing a car that is essentially ready to be built tomorrow (which is what you are asking for to see a Beta), then you have *way* too high of expectations.