Ebook piracy shows no such thing. What is shows is that when your trying to sell something in a market where the cost to copy is nil, then your business model is broken. Artificial scarcity on the internet is simply impossible and at best all you can hope for is to get people to pay for convenience.
Obviously writers can't make money through concerts or t-shirts; but there will always be a market for those of us of enjoy real, physical books. There is also a market for public speakers, many of whom are writers. Does this mean that all writers will be able to make a living? No. However it's neither reasonable nor feasible to allow everyone to make a living doing what they enjoy.