Minimum luminosity/contrast requirements for visible focus indicators

Hi all,

Are the LVTF looking at a minimum luminosity/contrast requirements for a 
future SC a la 2.4.7? [1]

How 'visible' an indicator needs to be is not defined in the SC.

Thanks

Josh

[1] 
https://www.w3.org/TR/UNDERSTANDING-WCAG20/navigation-mechanisms-focus-visible.html