Is it possible to present Markdown rendered in an Emacs buffer using Emacs\' own buffer text formatting capabilities? Emacs in graphical environments has rich text presentation
I guess you can use the source code of latex-preview for inspiration or pretty-lambda(a much simpler piece of software).
Alternatively you can convert the markdown to html in a background process and preview the html.
Everything is possible in Emacs, but not everything is easily achieved :-)