Every coin in existence was mined, and every coin ever issued will be. Miners are the network's security budget — and if you kept an Ethash-class GPU rig, it still works.
XHash is Ethash-derived: memory-hard, GPU-competitive, and altered precisely so that the existing stock of Ethash ASICs cannot be reused. Your GPUs carry over — the software changes: mine with Hashwarp, the official open-source miner, or with SRBMiner-Multi. Epochs are shortened to 720 blocks (about five days per DAG regeneration at ten-minute blocks).
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Mining income is subsidy plus fees, paid in full. Profitability still depends on your hashrate, hardware efficiency, and electricity price — and on a young network, total hashrate (and therefore your share of it) can move fast in both directions. Difficulty re-targets every block. Run the numbers before you buy hardware; nothing here promises a return.