SSR and OKW both have walking trails to Downtown Disney. Not sure if the two intersect or not, but if all else fails you could always use a route from SSR to OKW that passes through the DD area.
I'm not aware of anything on the slate that would connect SSR to PO. PO is on the other side of Community Drive, and pedestrian traffic on main roads seems to be a big WDW no-no. For that reason alone, I wouldn't count a trail being in the future.