I think the states pretty much have to follow the rules for this election, that were in place at the time of this election. They are all winner-take-all states, so whichever candidate wins the populate vote in each state, that state has to send all electors who are pledged to support that candidate. They could change the rules for how electors are chosen, but I think any such change would have to wait for the next election to take effect.
I suppose, if anything they could intentionally choose electors who have publicly pledged to support one candidate, but who have secretly agreed to support a different candidate—an intentional, organized form of the
“faithless elector” issue.