You seem to have a very low view of Islamic understanding of their own theology.
Lemme put it to you real simple-like: if someone were to discover the Bones of Jesus Christ, there would be NO POINT in fighting for Christianity. It would all be over. There would be no point in the Religion anymore.
ALL Christians would give up on everything, tomorrow. Total religious apathy across billions of people. Total cataclysmic immediate Faith-Death, everywhere.
The same thing would happen to Islam, if the Ka'aba were destroyed.
It's the whole ball-game, for a thousand and more years, in one City Block.
Islamists aren’t rational people. That’s the part you don’t quite understand.