PSP had more support then psv+3ds combined.
If a handheld release with a much better support then PSP i'm sure this handheld will outsell it
PS4 - over 100 millions let's say 120m
Xbox One - 70m
Wii U - 25m
Vita - 15m if it will not get Final Fantasy Kingdoms Heart and Monster Hunter 20m otherwise
3DS - 80m