I am also looking for a similar feature.
I have installed markdown-preview and critic-markup but once I have critic-markup installed, markdown-preview no longer works to open the preview pane.
I’m not sure why these would conflict. Looking through the source of the critic-markup package the only thing it seems to do is bind a few commands to insert critic markup syntax into the text. It should still open the preview.
In the end I’m really looking for a markdown preview package that has support for CriticMarkup. What would be the best way to achieve this?