I hate the word irrelevant when used in a context similar to this. Irrelevant is a definate, and implies that Nintendo have no holding, or no effect on the market what so ever. Which is wrong.
As much as you don't like them, and as much as they don't sell as well in the Western world, you cannot say it holds no relevance in the market. They have some of the biggest selling titles in the market on their consoles with the Marios, Zeldas, Pokemon and Super Smash Brothers, and with new titles for those games coming soon Nintendo is far from long gone.
Coupled with the child freindly online features, the easy downloading, the cutesy graphics, the novelty game controls and the unique social features Nintendo own a corner of the market, and will for a long time yet to come! (Especially in the East)