Salam Abdurrahman
These are circumstances created by the Saudi Authorities. We will not be asked to explain or give reasons for actions/circumstances created by others. If, they are wrongfully barring people ( believers from Ahlekitab, women without mahram etc) who can rightfully visit the kaaba ( right to visit the kaaba given to them in Quran) and making the visit for them unduely difficult, it is something that they have to answer to Allah for, not us.
Why will Kaaba, Mecca and other holy sites lose their sanctity for the actions of a misguided people? The Kaaba, Mecca and other holy sites retain their sanctity regardless of what these people are doing or will do in the future.
The Quran is not being properly followed by a lot of people who claim to be muslims, but does that mean the Quran is not a book of guidance anymore?
No, the Quran remains the authorised book of guidance for believers, if we are not following the Quran the way we are supposed to, we have to answer. Our actions reflect how we are, it has nothing to say about the Quran's ability to guide muslims.