ya sharding would work unless someone placed a huge bet on a sharded chain in which case it could be stolen.  it's just a subnet for processing transactions.  That's why I recommend above, a limited transaction size for each sharded fork. 

It's not a way to hard fork a chain.  It's a way to process more transactions by creating a number of smaller networks.  By splitting the transactions to subnets, "sharding" allows the system of networks to handle "spam" transactions aka micro payments.