Yes, there is something to be said for inertia. However, there are also a few characteristics of the SNES and PS2 that gave them an edge in an otherwise equal playing field. Most notably, their game libraries quickly got a reputation for being home to a great deal of excellent titles of all genres, while their competitors only had a fraction as many must-play games. Brand loyalty did help a bit, but ultimately, the main driving factor in the market at that point was the plethora of games that suited multiple tastes. When the interface is near-identical across the board, the software quality and diversity takes on ever-greater importance.
That said, I'm sure the massive third-party support showing we'll see for the Wii by the end of this generation, compounded with the massive first-party support, would essentially assure the Wii's successor a head start against its competitors even if it was just a Wii HD.
Sky Render - Sanity is for the weak.
