Actually, it's four, not five; there were several conditions to the "deal" that would allow Congress to easily weasel out if the matter ever were to come up; and in any case the particular clause is generally considered by legal scholars to either be no longer valid, unconstitutional or both.
Besides, every state is free to split itself up whenever it wants, however it wants, as long as the given state's legislature and Congress both agree on it. Article IV, Section 3.
YIKES!...Can you imagine, taking the concept to it logical ends..How many counties/parishes are in the U.S.A?...like W.V. in 1863 during the civil war?... :/