Please. If Williams can prove Nakajima isn't preforming, which I doubt they'll have to, Toyota won't stop them from dropping him. I mean, why would Toyota force Williams to keep a driver they wouldn't even employ themselves. The Toyota name is still printed on the Williams Car and on Nakajima. They don't want poor results with their name on it, no team does. Besides, Williams are clearly adament in getting Hulkenburg a race seat seeing as Hulkenburg is deffinetly a rising star.
I thought that Williams got the engines free/discounted because they have Nakajima?

Toyota wouldnt care too much about his performance just as long as there is a Japanese driver in a Toyota powered car.
But better no Japenese driver than a bad japenese driver. They want someone to represent Japan, not make it look like the country can't produce decent drivers.
Also, I'm sure the extra points and money earned by Hulkenburg would surely make up for the extra engine price. As for Hulkenburg being busy with GP2. Every GP2 driver has the same goal, F1. Any one of them would instantly drop out of the series if they were offered a seat.
Interesting though, Toyota TD Kamui Kobayshi is going to win the GP2 Asia series next unless he's struck by lighting or something equally impossible. I wonder how Toyota are going to start pushing Kobayshi then. Toyota president speaks highly of the guy.