Yes, in product terms I think 5-7m would be a regular sized launch of a big product. It could be done. In console terms, no one has ever done it because of the tech that is normally involved. MS launched with an almost experimental GPU in the 360, Sony did launch with an experimental CPU in the PS3. Before that PS2 needed a lot of specialist manufacturing capability, EE+GS was actually made in house at Sony and required Sony's semiconductor's business to invest a shit load to get production up to speed, and back then Sony never really outsourced so the shortages lasted for almost a year while capacity was brought online.
Now with TSMC making the APU, Hynix and Samsung making the GDDR5 RAM and Toshiba making the HDDs and Blu-ray drives, the PS4 is the first real outsourced console, which means they can place big parts orders and let the suppliers worry about delivering.