Gottlieb told lawmakers last week he heard them "loud and clear" when Congress legalized hemp-derived CBD late last year. He said he's putting together a working group of senior officials to write the regulations. He said the FDA would hold its first public hearings in April and outlined some possibilities for what the regulations might look like.

While the federal government in December legalized CBD that's derived from hemp, a close cousin of marijuana, the FDA's rules still prohibit companies and restaurants from adding it to food or drinks. Cannabis start-ups, food companies and restaurants have pushed forward anyway , introducing CBD-infused seltzers and lattes in anticipation that the FDA would eventually tweak its rules.

Just a week ago, it looked like the Food and Drug Administration was ready to revisit its policies around CBD-infused food and drinks. That may have changed this week, when FDA Commissioner Scott Gottlieb announced his resignation.

Then on Tuesday, Gottlieb surprised executives with his announcement that he's stepping down in about a month, possibly before the hearing and certainly before any policy could be written and implemented.

When asked whether Gottlieb's resignation was good or bad for the CBD industry, one cannabis investor said that's the "billion-dollar question." He said it could go either way, while asking not to be named because he's not allowed to speak publicly.

Gottlieb's successor hasn't been named. Whoever it is may have strong feelings on the issue or may decide to ignore it. The farm bill that legalized hemp-derived CBD also preserves the FDA's authority to regulate products containing CBD.

"In times of transition, issues like this that are not of highest priority could get delayed," said Jonathan Havens, co-chair of the cannabis law practice at Saul Ewing Arnstein & Lehr. For the industry, he said, the worst scenario is the FDA decides not to care about the issue.

Either way, the next commissioner will determine what happens with the industry.

In the meantime, it remains unlawful to add CBD to any food or drink.