Will be a visual editor wiki and when?
I’m not aware of any announcement that the visual editor will be installed. The way in which wiki functionality is added feels a bit unpredictable to me, though. There are other extensions (e.g. translate extension) which were planned to be installed, but weren’t so far.
The question whether it should be installed has been discussed a few times in the past. Or wiki relies on templates (especially templates like {{tag|amenity|bench}} in the middle of the text) more than Wikipedia, which probably makes the visual editor less convenient to use. But then again, we could simply make its use optional and non-default.