While its true there is still a relationship back to ICANN for ccTLDs, politically it would be a shitstorm of epic proportions if the US/ICANN interfered in the administration of ccTLDs - most countries (understandably!) see their ccTLD as an increasingly sovereign thing that is naturally owned by the State, not the registrars or domain name registration system.
While it might be technically possible for ICANN to make certain adjustments to the ccTLD system or the registration requirements, politically its much much harder and gets harder still with time. Imagine the response from most soverign states etc if their own ccTLD was meddled with in a manner they didn't appreciate.
ICANN has slowly tried to move more and more of the ccTLD stuff to international working groups ("Governmental Advisory Committee") to put clean air between the US and ccTLDs, but the link is still there:
ccTLDs delegations are managed by IANA, who are owned by ICANN