CX elite qualification mile
 

If I only fly AA and bank the mile into CX, can I be upgraded to Silver, Gold or even Diamond member. I saw no explanation on this. But I see the T&C says clearly that the OW airline mile qualifies for the member tier. It does not mention that one has to fly CX at least several times a year. Is it true?

Yes, but you have to join MPC, not just AM. Qualifying flights will be counted. You CX counts Club Miles and Club Sectors that need not be on CX metals.