When a leader speaks, their words carry weight, and that weight increases with the seniority of that leader.
As a leader, if you speculate in public, or otherwise express worry or doubts about a topic, those doubts will spread to the people in your team and beyond rapidly.
The only time you should speak openly about doubts is when you are talking to trusted peers or a mentor, when you can safely speculate about uncertain topics without concerns for that spreading, and more importantly to receive good advice from those you trust.
If you are uncertain, then it's best to say nothing and commit to nothing. Do not present anything until the facts are clear, as open speculation in uncertain times will do more harm than good.