No legacy ever really goes away. However it slips into irrelevance unless it's built on sound foundations that can be evolved. Sad to say, no PoW currency has a

No legacy ever really goes away. However it slips into irrelevance unless it's built on sound foundations that can be evolved. Sad to say, no PoW currency has a sound foundation that can be expanded and evolved... like tcp/ip has been able to evolve over the last 40-50 years.