is this working in this way?
if we reach 2mb traffic the client change automatically the limit to two, if we reach 4mb the client change again to 4mb, etc...?
if this is correct and it working as intended, i think it's the best solution out there
but what is the limit? otherwise some miner could force the system to adapt 3 GB blocks within 1 year or so.
BIP 106 does not dictate any limit. It adjusts the block size max cap according to network demand. To force the cap to 3GB within 1 year and keep it there, one miner has to have majority hash power, with which he can easily do 51% attack. So, it is a most unlikely situation. But, even if it happens, the algo will bring down the cap as soon as the miner is out of majority hash power. It is a demand driven approach, just like difficulty.
I think block sizes should be increased as & when it is required. Maybe 2MB for a while & then when the network dictates it increase it again to 4MB & so on.
I think it's ridiculous to be thinking about 8MB & 20MB blocks now.
That is you invite frequent forks, which is most undesirable in a sustainable system.