This verse also changes the "blind pharisee" from the plural to the singular, the verb is singular so it is addressed to an individual, not the group. The word "clean" is a command, which Jesus has not used in this section. In my reading, this indicates that he is answering the question of a specific person.

The "inside" and "outside" here are different words than used in the previous verse, Matthew 23:25, but they are from the same root. The hidden reason for the change of word form is the double meanings of these words. The word translated as "the inside" also has the sense of "insider" and "special."  The word translated as "the outside" also has the sense of "outsider" and "common." The sens is that if the "outsider" or "common man" is clean, he becomes special, an insider for being clean. The context of this section is the comparison of large and small. The interior is always smaller than the exterior.

The verb as "be" actually means "become," in a form that means something transforming by or for itself. This is a keyword here. Mistranslating it destroys Jesus's meaning. It is not the future tense, as translated in the NIV, but in a form of possibility. It doesn't certainly happen but it could or should.

The words, "and the platter," are not in some versions of Greek. The pronoun translated as "of them" later in the verse is singular indicating that this phrase was added the "and the platter" at some later date to make this verse conform to the previous verse.