Thiago won't be the last quality player that moves away from La Liga, Barca and Real are the only teams that can compete with wages payed by PL clubs and there are only so many players these two teams can employ.
Of course Barca fans will be pissed that they lose their probably biggest talent and of course they will claim it's only because of money, we do it as well every time a player we would have liked to see here signs for Chelsea or City.
But tbh I couldn't give less of a shit what Barca fans think if he really sings for us, I'm just happy that we got a really good CM which we have needed for some years now.