Is prophecy always centered on Israel?
Yes, prophecy is always centered on Israel. Even when it deals with Gentile empires, those empires are in view only as they have contact with or conquer the nation of Israel. Daniel's prophecy addresses Gentile empires specifically in relation to their involvement with Israel.
Les teaches that Daniel is a prophecy that will deal with the Gentile empires as they have contact with the nation of Israel. That is why, again, prophecy is always centered on Israel. It will include those Gentile empires that included Israel in their conquest. So while Gentile powers appear in prophecy, the central focus remains Israel, and the Gentile empires are addressed in connection with their dealings with Israel.