The block is valid only if the transactions are in the correct order, but the miner is incentivized to figure out the right order (specifically incentivized to

The block is valid only if the transactions are in the correct order, but the miner is incentivized to figure out the right order (specifically incentivized to include as many transactions as possible). Edit: You are always spending a specific input, so to broadcast B->C, B would have to wait for A->B and specifically name that transaction. The miner _could_ receive these transactions out of order, but that should not be an issue.