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The critical issue is that both are not able to scale to handle tens of thousands of transaction per second safely. So, like gold and silver, they are on the way to be relegated to just a secondary currency ...mainly for store of value (which in my opionion is looking bleak for the longer run)

IOTA could be an interesting alternative, it needs to stand the test of time, but now that it is possible to use with out a coordinator, essentially making it decentralized, it starts to look promising.