With what the Mazda models are offering right now, there is really no place for the Mazda CX-4 which was probably why Mazda choose not to offer it here in the US but that might change soon if rumors about the Mazda CX-5 moving up is true.
There were talks about Mazda looking to upgrade the Mazda CX-5 so that it sits higher int eh market. New spy shots of the Mazda CX-5 suggest that Mazda is looking to make the CX-5 into a premium model. If that happens, the upcoming Mazda CX-5 might come in with a bigger price tag.
A price hike would mean that Mazda will be leaving a gap between the Mazda CX-5 and the Mazda CX-3 and that is where the Mazda CX-4 could come in.
We still do not know what Mazda has planned for the Mazda CX-5. Hopefully, more details will be released as we get closer to the announcement date.