Yes, BlockQuote can be used as a generic block container. It doesn't have attributes itself but you can put them on a header at the start. For generic inline elements you can use Code.
Markdown syntax for generic containers (Div and Span) hasn't been implemented yet but the discussion is fairly mature now:
Markdown syntax for generic containers (Div and Span) hasn't been implemented yet but the discussion is fairly mature now:
https://github.com/jgm/pandoc/issues/168
https://github.com/jgm/pandoc/pull/1791