Following the “principle of least surprise,” what might people expect when they see non-marked-up text beneath blockquoted text? The author’s intent is unclear. It could be:
<footer>
<cite>
- Just plain text
I’d favor adding a little syntax in order to distinguish between different elements.
For example, figure with figcaption:

[A convenient caption below my image standing alone in a paragraph.]
Blockquote with footer:
> May the force be with you, always.
>
> [Master Obi-wan Kenobi.]
And an idea for blockquote with cite:
> May the force be with you, always.
>
> -- Master Obi-wan Kenobi.