And if the miner includes the transaction and his block is mined by others? Would the transaction be free for the sharks?
Yest that can happend,
it is bad luck, in that case there is nothing to do, but:
An orphan block is a block that has been solved within the blockchain network but was not accepted by the network. There can be two miners who solve valid blocks simultaneously. The network uses both blocks until one chain has more verified blocks.
So all depends of how many miner power you have to make your mined block the one that is accepted by the network, maybe only broadcast the block if you mined two simultaneos block in a row (the network must accept this as block winner)
Right now is not profitable wait for two simultaneus blocks to be mined, current block reward is 6.25
BTC, but in some weeks it is going to be 3.125
BTC, maybe then it can be useful or maybe in the near future when block reward is under 1
BTCMaybe futures puzzles like 67, 68 etc.. may fit in that criteria, but all this is just speculation.
Regards