As large SSDs are expensive for PC users (especially large ones), I think there should be a 2in1 type of HDD.
For example in addition to normal mechanical architecture, there can be a 40GB SSD module embedded into it. This will help in getting faster boot-up / loading times (using SSD) as well as large capacity for storage (using conventional HDD).
When these drives are installed there will be two physical partitions for user, one SSD & one HDD.
It can be called DDD or DD Duo (Disk Drive Duo).
The issues that will be important are cable interface & what if one of these malfunctions?