Should, as in, it would be the best way. It is not necessary, e.g. not required for the law to be in force (since the derrogated norm has the form of (presumably) a statute, not of a constitutional ammendment), but to make sure the new norm has the necessary status amongst the people, the lawyers, judges, etc., and to make sure that they can not get rid of it by a mere statute, it should be an ammendment.
So it is not necessary, but preferable. Are there any risks in amending the constitution? It has been argued that amendments to the constitution (specifically the 14th amendment and the 16th amendment) have contradicted the essense of the constitution and have been manipulated by foreign banking interests in order to usurp power from the people and the states. This argument has some merit and the power of the New World Order at the time was limited compared to today. So, wouldn't the risks to opening up the constitution to further perversion, given the New World Order's current control over our daily lives, outweigh the perceived benefit?
"Legal persons are not equal to natural persons. Their rights are not protected under the constitution."
and I would add "Legal persons have to expire in ten years" - as they used to in Old America.
I would rather see that there is no such thing as any "person" other than a human being. Giving corporations the power of personhood is dehumanizing, whether it be legal or natural.