I personally don't have hard data on it, which is why I used qualifiers such as "likely" and "people expected". Tesla has repeatedly said they expect higher demand for the Y and that fits with what usually sells well in the market. Plus it addresses common complaints about the 3 being "too small" and about the X being "too expensive".
I’ve seen them say that and in the general it’s true, but Tesla has been hush on revelaing any sort of demand with the Y and it doesn’t seem like the Y is that much bigger than a 3 to entice those people who’re holding out on a low end Tesla due to roomy interiors.
In most markets, sedans are in decreasing demand and the popularity of SUV/CUV vehicles is increasing. By that, the Y should be in larger demand than the 3.
Also, the Y addresses some of the tradeoffs made for efficiency on the Model 3: the missing hatch and the low second row. The Model Y will have a proper hatch, more cargo space, more vertical space in row 2 and optionally even a 3rd row of seats, increasing the attractivity for families with many children.
Putting that together, there is a lot of reason to assume the demand for the Model Y might eclipse the one for the Model 3.
People with families strongly prefer crossover models and they've mostly pushed sedans out of the market. It would stand that an electric crossover would outsell a 4 door sedan.
Wouldn’t families strongly prefer a larger car period? Is the Y really that much bigger that it’d convert families who are holding out on a 3 due to size? I haven’t seen anything to suggest as much, and both the 3 and Y are def less roomy than other (albeit non electric) cars that families go for.