You go from 1B to around 5B (around 680B Y at the moment which would be around 5B USD) market cap and call it "easy" :)
Form the current market cap, that's already 5 times what they wanted to pay for Leyou and this is without any premium (probably at least 30% if not way more) so 6.5B would be the bare minimum. I do not think this is an easy thing for Sony. I suspect anything lower than 8B would not be accepted by SE Board too.
In any case, I believe Sony can get the money; but as SE is already doing so many exclusives for Sony; I don't think this would be a very good business decision; they should spend their money on something else imo.
You're right. I undervalued SE there.
Still, I realise they picked up Bungie for 3.6B, and they're far smaller than SE.
I think what they get makes the investment worth it (though I think there are better pick ups)