It looks like Ducati CEO has confirmed that more bikes with V4 engines are currently in the pipeline. According to the article there are as many as 29 new bikes planned in the next 5 years. https://in.newshub.org/more-ducati-v4-models-confirmed-29316977.html#
"We will continue to develop new versions of existing products but will also be entering segments that we are not currently in. As part of that, we will exploit the V4 engine in different platforms,"