I think its better to note that he is speaking to the (corrupted) politicians of his day, and he is protesting. This is Jesus speaking against the discipleship methods of his day to the politicians, but he's talking about more than that, too. Their basis of authority is what he is talking about, and he's saying there's no basis for it. Jesus is portrayed here alluding to Jeremiah 31:33 in a mystical way that its time for the law to be in the heart instead of taught by one master to another. Either he is saying that the laws are in the heart now, or he's saying that eventually they will be. Whichever the case he's saying the leadership are not needed. Its possible, too, that Jesus is claiming that the time of renewal has come or some complex related event.
One of the things Jesus says in John 3 is that the spirit goes wherever it goes -- meaning it doesn't have to pass from mouth to ear. Hence there is no need for wise elders. Hence there is no need for these corrupt politicians, and he is also telling them that they are mean and heartless and that their faults are the reason they won't accept his words.
Some people, probably most, saw things differently than Jesus. They didn't think that it was time for 'Holy to the LORD' to be inscribed on the bells of the horses and cooking pots. (Zech 14:20) Jesus on the other hand was prophesying "The kingdom is here" meaning literally they were already in it and just needed to accept it. The Romans all around them, these were the 'Bells' and the 'Cooking pots' in the prophecy. People generally didn't see things that way although many probably wanted to, and Jesus clearly had a following. What most saw and what those corrupt politicians saw was a crumbling world, a ruin. Jesus on the other hand seemed to think it was time to spread out and to view the situation very differently.
Exodus 3 does not apply directly. He's really alluding to "No, the word is very near you; it is in your mouth and in your heart so you may obey it." (Deu 30:14 NIV) He's saying that for some reason the word is not near them, not in their mouth and heart (Note he's saying this to some politicians of his day not to all Jews). Jesus words may sound very harsh but in the context of his ministry they are just recapping his view of the situation. What he is saying to these men is that they are deeply in error, and he is warning them prophet-style that they do not love justice and mercy. He's also saying that they are not irreplaceable. Basically he is saying "You should be listening to me, but you're too stubborn and mean and therefore blind."
