Goku is smart?

Wait' in order to acheive magenkyo sharingan,one must take the eyes of another uchiha.
If so where did itachi get his.

*slaughters whole village of Uchiha*

It's like they were growing on trees, for God's sake. All he had to do was walk over to one of 'em and pop out the eyes!

God,I need to re-read the manga.I'm lost.

I thought for the Eternal you need to take your brother's eye

Like with madara?
And what about kakashi?

no, it can be from any member of the uchiha clan. To get your whole vision recovered you need the eyes from someone such as a sibling.If it was just anyone, then then the eyesight wouldnt fully recover unless, you've used you rmangekyo just once in which case any uchiha would be ok.
@Noyk Madara was given his brother's eyes so then His eyes fully recovered. It hasnt been revealed how Kakashi awakened his Mangekyo

that being said,what about kakashi?

My theories are
1 He had it all along but it put WAY too much of a strain on him to use it at all in Part I, and I remember they said Kakashi once went into hospital for months because he used it too long, it may have been referring to that.
2 Rin was dying and he put her our of her misery in the timeskip.

Do you think Kakashi will ever get Eternal Mangekyo

doubt it.

I think that Sasuke will enter when Naruto's and Kurama's chraka run's out

I feel the same way but I honestly think that Kabuto will have the biggest roll in Tobi's death