Yes, I believe it is. You could describe a syntax and invite other people here to share their thoughts.
Keep in mind, there’s already some variation (or is it fragmentation?) in attribute syntax among different Markdown flavors and other writing formats like Markua. For example…
Pandoc / PHP Markdown Extra / Earlier version of CommonMark spec:
{#myId .myClass key=val key2="val 2"}
{:ref-name: #myid .my-class}
{key_one: value1, key_two: value_two, key_three: "value three!", key_four: true, key_five: 0, key_six: 3.14}