PICK A GOD AND PRAY

I don't think they can.

Make better games than Nintendo, would be the first step. (But is this possible?)

Lol. I like how you portray Sony and MS as some sort of tag team whose sole objective is to destroy Nintendo.

No.

they have to buy them ^^

I don't think they are even trying. It's not like they are direct competitors anymore. Sony is busy enough fighting Microsoft. Also Shu likes Reggie. :P

The only company that can take Nintendo out of the race is Nintendo themselves.
How would they do it? Manage the rest of Wii U's life as badly as they managed its first 9 months.

make a profit first lol.

Nintendo will always make a profit so doesn't matter how much they sell.

I think Sony and MS are far more interested in taking out each other which will never work as long as they are doing much the same thing.