Wrong - a Chief Justice can be elevated from among the Associate Justices on the current court and the new nominee could simply be one of 8 "Associate Justices" - not saying that will necessarily happen, just that it could.
Say hello to Chief Justice Scalia or Chief Justice Thomas!!! :^) (maybe, I sure don't claim to know)
However, I don't see what significance the "chief justice" has. Last Feb., my students and I spent two hours with Justice Thomas, and he outlined how the Court does things, and he basically said the CJ has no special power, no extra influence, nothing. Just one vote.
"Say hello to Chief Justice Scalia or Chief Justice Thomas!!!"
I don't claim to know either, but that's what I'm hoping for too.