That's likely the point where spinning platters die in the marketplace.
Right now, spinning platters are around $12/tb. SSDs are around $75. Exact numbers fluctuate with features and market changes, but those are the ballpark. Cut in half, SSDs will be $38/tb, and then $19 in the next halving. Spinning platters aren't likely to see the same level of reduction in that time period; they're a mature technology.
I think once they reach double the price per tb, we'll see a major collapse of the hard drive market. My thinking is that there's a lot of four drive RAID 10 systems out there. With SSDs, those can be two drive RAID 1, and will still be faster. With half the drives, they can be twice the price and work out the same.
Spinning platters are already dead in many ways because even though they've increased in capacity, they haven't meanigfully changed read/write speeds in decades, which makes moving the ever increasing data a huge pain.
Most hardrives live in servers, as part of storage volumes where
IO can be optimised well beyond the capability of a single disk.
For the boot disk on my workstation I am absolutely using an SSD, but for the hundreds of terabytes of largely static data that I need to keep archived? Spinning disks all the way. Not only to SSDs need to match on price, but they also have a long way to come in terms of longevity.
Not really relevant, but I just moved 150ish GB between SSDs in a few minutes, less than 5 for sure. As a teenager such an operation (moving 3 games between drives) would have taken an hour. As a kid I'd be furiously changing floppy drives all day.