You should ask the CEO when when and how they plan to communicate the situation, and how you can help in doing that. Work on the assumption that staff will be told at some point.
If they prevaricate or indicate they wish you to keep the matter secret for an extended period of time (say, longer than 2 weeks), make it clear that you will not lie and that if the work dries up people will start to ask questions and you're going to need to have answers.
At some point the situation is going to become obvious to someone and unless everyone is told 'officially' in a short space of time, rumour will get round. Different people will know at different times and it will be hearsay. If the company is seen to be hiding this fact or telling people selectively, then it will be disastrous for morale - even if work picks up. People will start to look for other jobs because they won't believe theirs is safe (even if it is).
On a practical note, presumably at some point you're going to end up with no project work to give the team so you will need to raise this with your CEO as a time by which you expect the matter to be communicated. In the mean time, look for work which will make it easier for you to complete work well if it does come - paying off 'technical debt', improving your test coverage, automating things, research into things potential clients are interested in doing, etc.
You should also talk with the CEO about why there is no work for your department - do Sales understand the role you do? Are there reasons why the products you work on are harder to sell in general or different to the other things sales do? Are they focussed on selling something else, and if so, what and why? Is there anything you can do to make their job easier?
Note that if there is the potential for redundancies, many places have laws which mean you must tell staff and invite their ideas for avoiding or mitigating layoffs during the phase where you can do something about it (rather than after the point of no return). Even if it's not law where you are, it's the right thing to do and also a good idea if you want to keep your jobs. If you have a union, you may be required to discuss the matter with representatives shortly before making the announcement so you can co-ordinate communication about the consultation and any negotiations that may involve.