Hi TS Andy,
This is a relatively new policy from CX. Their scheme is similar to BA in that you earn points with CX / BA to gain status, but miles are accumulated in Asiamiles / Avios.
My Marco Polo status has now reduced to zero and in December 2016 I received this mail:-
Fly to renew your Green status
When club changes went into effect in April, 100 club points became the new requirement for Green membership renewal. However, we would like to offer you an exceptional renewal if you book any flight eligible for club points* and travel before your membership expires. Alternatively, you may pay an annual renewal fee of USD100.
The following year
Once you renew your Green membership, it is good for 12 months, and can be renewed for another year by flying 100 club points or paying a USD100 renewal fee. You can learn how the club points system works and how club points are calculated here.
Whether or not you renew, your Asia Miles account is not affected and you will continue to earn and redeem Asia Miles as you do now.
I hope this helps. As you can imagine, I let my Marco Polo card lapse and will rely on BA Gold for lounge entry etc.