Hi there,
What will I need to know about and do when WP takes that step, so that GeneratePress can handle things when that happens?
Hopefully, nothing.
If WP / Woo makes changes that require us to update the Theme so it works correctly with Woo, then we will do so.
I see no issue if woo releases blocks for cart and checkouts as those can be hooked in using a Block Element or added to the relevant static page.
But ultimately i doubt we will see the demise of shortcodes or woo forcing block built HTML templates upon us any time soon. There are way too many sites that rely on PHP coded templates and shortcodes.