documentclass{beamer}

usepackage{graphicx}
usepackage{lipsum}

begin{document}
    begin{frame}
        includegraphics[height=0.3textheight]{example-image-a} \
        begin{overlayarea}{linewidth}{0.5textheight}
            only<1>{
                begin{itemize}
                    item A
                    item B
                    item C
                end{itemize}
            }
            only<2>{
                begin{itemize}
                    item Dfootnotemark
                    item E%footnote{Footnote concerning E.}
                    item F
                    item G
                end{itemize}
                vspace*{2.5cm} % Push footnote approximately to bottom.
                footnotetext{Footnote concering D.}
            }
        end{overlayarea}
    end{frame}
end{document}