THe Mega drive had five variations, in terms of cross nation releases.
Brasil        SMS
Europe,     Genesis 
Korea,       Genesis 
US/Canada/Mexico Dreamcast
Japan  Saturn`Dreamcast
The PCE only has two, which is 
US
Japan
..................
SEGA had the entire US in thier market, and was juggling, three systems.
They even extended the life of the Saturn as another PCE, with Sagata.
In South America, the SMS was being sold, and is probably being sold today. Even now they have those portable Genesis consoles. Europe still demands for a Dreamcast and Mega Drive comeback. Dreamcast was NEC 
last hurray in the game market, as parts.
The PCFX was NEC making a PC, just for videogames.
The Supergrafx was already shotdown, by it's own brand.
I keep asking myself, why did they have to go from the suitcase unit to the Duo units?