This is the key to how this will all come down. The Alabama GOP is a private organization, and the ballot lists Moore as its nominee. It can withdraw that nomination, and if Moore wins, the election will be deemed null and void. Moore, whose political reputation is based on resistance and defiance of the law, probably can't persuaded to withdraw, but the local party can yank its support regardless.
The key to avoiding disaster is to have the Alabama GOP withdraw its support quickly, thereby raising pressure on the Governor of Alabama to postpone the special election to allow the Alabama party time to find another nominee (maybe Jeff Sessions himself).
The most likely result is still a Doug Jones victory, although the specter of an invalid nominee on the ballot essentially turns the race into an up or down referendum on Mr. Jones. He wins, he's the Senator; Moore wins, a new election is called.
The Wall Street Journal this morning opined as follows:
In the event Mr. Moore refuses to drop out in the next day or so, President Trump might have more sway if he suggests that he leave the race. If Mr. Trump won't do that, then the GOP will be better off if Mr. Moore loses, despite the blow to its Senate majority. Democrats and the media will make Mr. Moore the running mate of every Republican in 2018.
Alabama's Republican voters are in a tough spot, and ideally they'd at least get the chance to choose between a prominent write-in candidate or opt for sending a message by voting for the Democrat. For 25 years Democrats and feminists euphemized and apologized for Bill Clinton, starting with Gennifer Flowers before he was President. Republicans can show their standards are better.
This is the choice the Alabama GOP (and indeed, Alabama Christians) must make - to make a stand to be better and less cynical than the Democrats on the issue of CHARACTER MATTERS.