See this information from Tom Goldstein.

The fact that an opinion in McCutcheon has not come yet means it is not likely there was a majority to take Justice Breyer’s suggestion at oral argument to punt in the case and send it back to the trial court for factfinding.

It could still happen—look how long last term the Supreme Court held the Fisher affirmative action case before punting. But if a punt happens so late, it probably means it was not the original plan but something happened during the opinion drafting process.