Cost to zero? Definitely not.

Solar in space produces 30% more power, and doesn't turn off at night, meaning you don't need batteries. That means power costs, say, 25% of what it currently does measured against terrestrial solar and batteries.

The 75% electricity discount needs to pay for launch vehicles, specially designed satellites, and the inability to service the hardware or resell it when it's EOL for the data center.

It's a gamble. Maybe it'll turn out to be a slight edge, maybe it'll turn out to fail, but it's not a sure thing and it certainly isn't going to hugely decrease the cost.

Especially since they're competing against Google and their custom designed hardware that's far more power efficient for AI. It's not clear that NVIDIA running at a 75% dollar discount beats Google's best TPU in compute per dollar.