The problem with his arguments are several. One is that he does not acknowledge any kind of outer/inner distinction in the covenant. I believe that the covenant has an inner core which is unbreakable (the covenant promises salvation, and election, justification, adoption, etc. are *benefits* of the covenant). However, the covenant also has an outward administration (not all Israel is Israel, they went out from us but were not of us, and other passages), which is breakable. I fear that too many discussions of Jeremiah are marred by this failure to recognize the inner/outer distinction. From the least to the greatest is more likely to be a merism, which is inclusive of all members of the set, not exclusive of any. Therefore, I believe that Jeremiah is talking about the inner-core substance of the covenant.