MrT-Tar on 28 October 2010
I think the 3DS will sell 100m easily. I don't think the 3DS will match DS numbers overall (but I do expect better sales initially after launch) due to increased competition from the smartphone market. The 3DS will sell itself not only due to being the DS' successor, but also the 3D capabilities and to a lesser degree backwards compatibility.
I know that this probably isn't representative of the entire global gaming population, but everyone I know who owns a PSP also owns at least 1 DS (usually 2 or 3), suggesting that even if the 3DS takes a major bite out of the PSP2's market, sales won't increase that dramatically.
