It looks like the original heel to me and the heel is the first to need replacing.
Push with your thumb into the centre of the sole: if it feels hard, the sole is fine. If it feels soft and spongy, the sole will need replacing soon.
BS is right - soft and spongy means you're near the cork filling....
I see the picture is also exposing the stitches where its been channeled (around the edges). Many people seem to get overly
concerned when they see this. Perfectly fine.
With this amount of wear, is it advisable to get it topied at this stage?
Thinking of extending the 'sole life' as much as possible before a resole. I'm just afraid that applying topy will weaken the actual leather sole further.