The reason why the 5th Amendment must not be changed can be found in the preamble to the Bill of Rights:
"THE Conventions of a number of the States, having at the time of their adopting the Constitution, expressed a desire, in order to prevent misconstruction or abuse of its powers, that further declaratory and restrictive clauses should be added: And as extending the ground of public confidence in the Government, will best ensure the beneficent ends of its institution." (My emphasis).
Get rid of the 5th and what's next? "Oh, we don't want people saying bad things about the government, let's do away with the 1st Amendment". Then, "Oh, we don't want civilians to be able to protect themselves, let's get rid of the 2nd Amendment." Then, "Oh, we don't want people to have secrets, let's get rid of the 4th Amendment."
Far fetched? Ask the journalists at AP. Ask Verizon subscribers (and probably subscribers to all other wireless phone carriers). Ask Mayor Bloomberg and Sen Feinstein what they would like to do to law-abiding gun-owners.
The wedge has already be inserted and is being driven further in, blow by blow.