Just a quick thought about the effort going on to change the way California selects electors. First of all, fundamentally I have no problem with the notion itself. States should be able to select electors any way they see fit. Winner take all, proportional to an election, or even with methods that don't involve elections at all where the electors are selected directly by the legislature.
My radical proposal? Much like jury duty, select electors completely at random from the entire adult citizen population of the state. Unlike jury duty, excuse people from it ONLY for physical or mental inability to participate. It would be absolutely compulsory. Do the choosing only 48 hours before the electoral college votes, with absolutely no vetting in terms of who the newly chosen electors support. Make lobbying the electors on behalf your candidate illegal. An exception would be the electors themselves. The electors would be able to talk amongst themselves and lobby each other for the 48 hours before they have to vote. Sequester them at the moment they are chosen, deliver them to the state house to perform their vote, and then see what kind of results you get.
I imagine it would be a very interesting way of doing things. :-)
But in any case... if changes are made, although there may or may not be anything already enshrined in law to prevent it... I think any changes to how electors are selected by the states should be made one full election cycle in advance, so that all potential candidates can make their plans knowing the state of affairs for the full four year campaign cycle. That is only fair.
Of course, although I didn't mention it, in my radical proposal a state doing this would also have to exclude from the random selection those individuals prohibited from being Electors by Article II:
"but no Senator or Representative, or Person holding an Office of Trust or Profit under the United States, shall be appointed an Elector"