Merge (as Dan suggested) or Append are standard tools for getting features from different datasets into the same dataset. I looked at your data and these tools are not appropriate for your case because your datasets have many overlaps. You'll get duplicate geometry at these locations--two features in the same place.
The Identity tool (one of the Overlay tools) will work better because it won't create duplicate geometry. If Zoning is used as the input features and Future Landuse is used as the identity features, the output will have Future Landuse geometry wherever there are future landuse features and Zoning geometry wherever there are only Zoning features.
CAUTION! Your datasets don't align neatly and your output will contain lots of sliver polygons--places where a little fragment of a zoning polygon is mostly but not completely overlapped by landuse polygons. Also, the attributes of your datasets don't match. You'll have lots of null values in your output table. That isn't a crisis, but it could be a problem that the values in your zoning categories don't correspond to the values in your landuse categories. In other words, your output dataset will be a continuous polygon coverage, like you want, but it will also be helter-skelter with respect to geometry and attributes.
I don't know what your objective is, but I think you might reconsider trying to manufacture land-use polygons out of zoning polygons when the datasets come from different sources and weren't designed to be used together. Sometimes GIS tools give us more power than we should have.
