The matrix, as a whole, barely exists. what wasn’t blown away physicaly or torn apart by hackers is simply shut down due to lack of power. also, a lack of hard lines forces any node to be local only. most high end decks would have been damaged by time and probbly wouldn’t function.
a couple of large, powerful matrixes still exist. Deus controls the most important one. his sytem is linked (but locked out of) the ARES global defence net. his matrix is untouchable due to decades of tweaking and searcing for holes. several jack points could still hack into his domain, they just await a powerful enough decker.
Chitown and several large ARES settlements around it are also martix covered. this keeps the local population in line, as they are alwasy being watched and can be controled through it. the settlements are centrally controled and hardlined to chi town. the lines are constantly patroled and monitoured for damage.
Lung also has a sizeable matrix to maintain his virtual library. he is probbly the only source of old, powerful programs.