"there are two aspects here – performance and functionality."
Sounds like a guy who might actually know WTF he's talking about.
SSD has got cheaper and no ever doubted it was fast compared to disk.
But it's not as cheap as disk in the same that (at the right scale) tape is cheaper than disk.
Remember the first SSD? No.
Never heard of bubble memory ?
It was going to change the world. Everything was going to going to use it at every level.
Only it didn't.