From today's storage newsletter.
Only 2.7X ratio and less for flash drives of up to 2TB, but much more beyond this capacity
https://www.storagenewsletter.com/2019/01/29/price-comparison-between-hdds-and-ssds/
With 3D and QLC NAND coming the HDD market is only very high capacity and STX needs to keep jumping capacity points. With HAMR delayed at 20 TB+ and no MAMR solution flash is going to catch up fast.