It already is...

Otherwise Sony and Microsoft weren't launching their own motion devices to catch up with the wii

Not in its current form. For console purposes it is still juvenile technology and needs a whole lot of refinement and development before it can become omnipresent and relevant to all games. Motion sensing technology is not something new at all but applying it correctly to videogames will be a massive challenge (fighting games, racers, 3rd person action games, some puzzle games for instance). Nintendo may have taken a first step but the long trek is still ahead and we don't even know which direction it will go and where it will take us.
It is quite absurd to assume that the Wii-mote will be the be all end all of future gaming and the same can be said for Natal imo.

Many people don't really think it'll do well for hardcore games, but it will come.

As Mummelman said, it will take some time for motion controls to conquer all genres (though i'll say it already has conquered racing, if Mario Kart Wii is properly seen), but i believe that the controllers themselves will become standard starting next generation

What we'll have are modular controllers, something like the Wiimote + Nunchuk that can provide the faculties of a traditional controller and a motion controller at need. Such modular controllers are going to become the new standard, leaving developers free to choose their path as they will, but keeping the gradual evolution towards motion dominance.

This, this, and this again.

Yeah we CAN control shooter games with motion controls; but they are MUCH better with the regular joystick controls. Just look at Call of Duty 4. It came out last year and had 2 years to improve on the original and it wasn't even equal, let alone any better. Motion controls may be better for some genres, but not shooters.

And the fact that it was a cash-in port had nothing to do with that?

God I hope not.
Even if it happens there is always PC gaming :)

Motion control is the present.

No its not, Just like 3D isnt the future of movies.. You know why?

Not everybody likes it.