The question is how fast the disruptor (Nintendo) will move uptier to chase competition up to the even higher tier users.

Nintendo will have an HD system next generation, but it is unlikely this will be the key reason why it takes the lead. It's not graphics that win the markets, it never has been. It is about who has the games that people want to play. Nintendo has been the leader in creating new ways for people to enjoy games (with the exception of the Gamecube which was more or less PS2 Jr.), and that has been, and always will be a far more powerful hook than graphics unpgrades. The N64 failed because of pricing (games cost WAY too much) and availability (games on the N64 were rarely released, sometimes months would go by with no releases; that would be absolutely crazy nowadays, as the Wii usually gets at least one release per week).

Name brand recognition is strong with Nintendo, and it didn't begin with the Wii, it has deep roots; and remember, nearly a hundred million Nintendo fans existed before the Wii; there was just wasn't a console that they felt was worth buying - but they had Gameboy, GBA, and DS instead (even if those people originally bought Sony systems for console instead, they mostly jumped onboard with Nintendo this generation)

your words are exactly how i feel. although i think wii 2 will bring hd graphs for they will be too cheap to not do it.

nintendo shall bring some new tech, for the competitors are entering in the market of the wii very fast.

(of course nintendo has some killer applications the others dont: mario, mario kart, zelda, metroid, sports & fit, the wiimote pointer...)

OP: No, if Nintendo focuses more on graphics, it won't be the same recipe any more and there's no reason to think that ploy will work at all. All it would accomplish is releasing games with a high number of polygons with a very "childish" or stylized look so unless they plan to make all their franchises realistic and in effect ruin them, these games won't compete directly regardless of HD or no, just like Sony and MS' motion controllers won't compete directly with the Wii-mote.
Its not what the respective consoles are about at all.

Why is it that trying to follow Nintendo's lead is silly and will make you perish yet Nintendo can follow Sony and MS and gain from it? It doesn't work that way I'm afraid.

I do think Nintendo will move towards technological parity, but only because Sony and Microsoft won't make that big of jumps (maybe to systems with 2 GB of RAM and CPU's only about 1.5-2x faster). It would be easy for Nintendo to catch up, because on the technological end of things next gen will be about refining what was introduced this gen (smooth clear 1080p at 60 fps becoming standardized)