It has been presented during the Build conference, and now this is available for download: the Presentation Translator
You can download it from https://aka.ms/translatorpowerpoint and if you want to know more about it go aka.ms/PresentationTranslatorLearnMore
Once installed the add-on is available in the Slide Show tab
If you hit the Translate slide or Start subtitles you will be able to define from which language to which language you want to translate
