(C) can likley only come from well-intended bitcoiners trying to "fix" bitcoin.  The easiest way to attack bitcoin is to agitate for a civil war and split into two coins.  That is a bigger threat than a 51% attack, because it has happened more than once already, and a 51% attack has yet to happen.

Aside from that a well managed mempool is a way to manage fees, and mitigate agains fee based attacks, which we are just starting to see.