IMO, all Tesla vehicles (so far) are pretty similar to each other.
On the one hand, Y is a less expensive X.
On the other hand, Y is a bigger 3 with a hatch back.
I'm not an expert in automotive consumer behavior, but I have to imagine that Y will cannibalize some amount of 3 sales. I also don't think that will matter that much - there is so much demand for Tesla vehicles that they are battery limited.
So if it will probably take some sales from both the 3 and X. But X sales aren't very significant compared to 3 sales anyway.
The Y is a crossover SUV like the X, but based off the Model 3 platform/chassis; what I'm really surprised by is the notion that they will build these in Fremont!
I actually interviewed at the Fremont Factory in '17 in logistics, the factory was a at Max capacity even with the low 3 numbers being produced. In 18-19 they hit their stride and started to use auxiliary lots:
https://teslamotorsclub.com/tmc/threads/found-a-lot-of-model...
They stated that at full capacity and with a successful ramp up 3 would overwhelm their storage capacity, so turn around was critical with little to margin for error; if anyone remembers all the Tesla employee parking lots were full and created a parking nightmare. Well, the outbound deliveries were equally bad. The shutdowns and refitting of the assembly lines showed just how drastic things were for a while.
They overcame this and I'm glad they did as they are now offering the 35k base model 3 as was announced in the beginning which was the 'game changer,' but I'm also glad I turned down the offer in the end, especially because they don't seem to be utilizing their Sparks and Shanghai factory for this model which would probably be best as S/X/3 are still being made in Fremont. Then again that stock price leap to 600 is pretty nice, just not worth the stress induced heart attack or stroke at 40.
I wonder where Semi/Roadster II/Cybertruck are being made then. I honestly thought they'd consider doing the Roadster II at Fremont for that extra 'Made in California' cache to match its price tag, but not the Y.