Powerpoint will continue to persist because other people need to be able to edit your slide deck without understanding your HTML.
My employer blocks office plugins, so I can't try Claude for PowerPoint, but sometimes I get Claude to generate Python scripts, which produce PowerPoint slides via python-pptx. This also benefits from being able to easily read and generate figures from raw data.
I don't really like the way Claude tends to format slides (too much marketing speak and flowcharts), but it has good ideas often enough that it's still worth it to me. So I treat this as a starting point and replace the bad parts.