Thanks for commenting Chadiga.
The Qur'an says that if was not from Allah, we would have found many contradictions in it.
Sure, when the Messenger was alive, Allah told those who were formulating their beliefs, what the role of a Messenger is. Had they any doubts, verses like these helped to settle for them which camp they belonged. It told them, for example that their allegiance belonged not only in terms of a verbal acceptance but it was more than that and it involved their whole hearted support.
I agree wali (protector, along with Allah) was valid when the Messenger was alive. Now we have only ONE Wali who is Allah SWT.
If we read the principle here, all else falls into place:
3:79 Never would a human being, whom Allah has blessed with the Scripture, Wisdom and Prophethood, thereafter say to people, "Be servants of me instead of Allah. Rather, he would say, "Become true devotees of the Lord since you learn and teach the Book and study it as it should be studied"