I never meant to take it as a promise, but it is likely still. At the very least likely enough to not outright reject it as fake.
From what we know now there is a Swiss F/A-18C planned for the German techtree at some point. This is most likely sometime after the next update, but seeing the relevance of the gap it would fill, before the Eurofighter is added.
It could still never be added, but that seems less likely than it being added by our current state of information.