Has it really been effective? Barring intervention by the governor or the sheriff, what will happen is that she will be fined, imprisoned, and removed from office by the Federal authorities. The county will thereafter issue marriage licenses to same sex couples. She will have her "15 minutes of fame", but will thereafter be forgotten, except by conservative Christians, who are a minority of the population.
The governor of Kentucky and the sheriff of Rowan County have taken an oath to uphold the laws of Kentucky. If they refuse to interpose their authority against the Feds, they have broken their oaths of office.