Is Prophet Muhammad PBUH the last prophet?
Most if not all Muslim scholars confirmed that 'the seal of the prophet' meant there will be no more prophets after Him and they are almost absolutely sure of this.

Whenever I notice anyone being very sure of himself, I will every time without fail, explain to him the danger of being very sure of something by relating the story of King Josiah in Scriptures. King Josiah was a good king. Everything he did was pleasing to God. One day he decided to wage a war against the king of Egypt, King Neca. King Neca wrote a letter to King Josiah telling him to refrain from waging a war against him because Almighty God have instructed him to wage a war against his neighbour and to do it quickly. Now the king of Egypt is a pagan king so King Josiah was absolutely sure that King Neca is telling a lie because he was under the impression that 'God do not give instruction to pagan kings'. Moreover if God wanted to destroy a nation surely God will choose him to do it and certainly not a pagan king. So King Josiah in his 'good judgment' decided to wage the war against King Neca of Egypt. Believe it or not, the truth was God indeed had given instruction to King Neca of Egypt to wage a war against his neighbour and to do it quickly. No prize for guessing what will happened to the king who wage a war against another king with God on his side. Two arrows pierced through his body and he died. Remember that everything King Josiah did was pleasing unto God but this time around he committed the sin of presumption, being absolutely sure of something but later found out to be wrong.

I could agree with them all that Prophet Muhammad PBUH was the last MAJOR prophet but certainly there are many minor prophets sent by God to instruct mankind the right path and until today there are no shortage of such prophets. We may not recognise them but they are certainly around given instruction that are usually disturbing to religious leaders.v More often than not, these prophets are sent when the religious leaders or kings erred in their ways.