Use html tags in shortcode_atts, is it real?

While it is a technically possibility, it’s most likely direction that isn’t worth it.

Overuse of shortcodes for what is essentially (crappy) templating is problematic and has a history of security issues.

In recent months there has been ongoing planning and discussion about possibility of changes to shortocde syntax and mechanics in core. HTML in attributes is explicitly named as one of the problems that led to it.