There is one thing I don't understand about the MLSAG signature.
The additional public keys mixed into the signature ring, must correspond to real unspent outputs in the blockchain, isn't it? Otherwise one could identify them as just obfuscating keys.
But in that case traceability will increase over time, at the pace those additional outputs are spent.
S. Noether's paper is not very clear at this respect, so perhaps I'm not interpreting this correctly ... Is there another source that could shed light on this issue?