The trend is clear: it won't be long before conservatives accept it as an economic necessity.
What do you mean by economic necessity?If states want the tourist trade or seek to attract businesses of same-sex couples, then those states may legalize SSM for economic reasons even if the partisan makeup of the State legislature is 'wrong'. Thus if Michigan and Ohio legalize SSN. Indiana follows along or pays a price.
It would be even more effective to ensure that only Christians could inherit money. That way Jewish families could be fleeced of inheritance taxes, and such would be good for public coffers. It would obviously be objectionable for other reasons.
Discriminatory taxation is of course unacceptable.