We can easily alter them forever. One MOAB over Mecca. That is all it will take.
The jihadists will not miss Mecca. The Sauds maintain it as a tourist attraction for Moslems. The Hajj is still required even if Mecca is a glass hole.The buildings don’t really matter so much except the Ka’aba but they could do without that, to, because it would only be gone because Allah willed it. The Sauds are tearing down most of the historic structures outside of the Grand Mosque that have religious significance because of that religious significance. The existence of a house that Mohammed lived in was thought to attract reverence due only to Allah. So the house was recently torn down to make way for a hotel to serve the Hajji.