With 4 Americans already there, you won't see much movement from our side of the pond to theirs. When Edwards and KRjr retire, you can count on Yamaha to find a fast 250 rider to replace him, either Spanish or Italian. As for KR when he leaves, daddy will probably call Kurtis in for development duties since he can be had cheap.
Remember, a GP ride is at least as much political (Spanish rider on a Spanish-run team with a Brit rider to please the British sponsor) as it is talent.
Never pet a burning dog.