If you are then... "We'll keep you posted." "up-to-date view of the runway ahead."
Where do these things come from if you're not estimating effort?
The only thing you can really confirm though, is what is already completed, and that is what you should keep the stakeholders posted on. And a description of work left, not necessarily the time it will take.
This is the work left, we think it's this size*, this is how much work we've been getting done. It looks like we might be done at this date but that's dependent on a) our estimation being correct and b) our pace continuing.
I think it's more about managing expectations than it is about managing the information you let stakeholders have.