The alternative is to do things off the grid, so to speak - meet people in person, exchange funds for cryptocurrencies. Actually that might be a small side business idea.
Of course, one of the goals of cryptocurrencies is to not have to go through central organizations at all. Not converting your cryptocurrencies back to fiat, and not storing them on an exchange will be the best way to dodge taxes. Pretty sure that if you hide your keys well enough, the IRS and co cannot prove that you have any assets in cryptocurrencies as long as how you acquired them can't be traced.
Of course, one of the goals of cryptocurrencies is to not have to go through central organizations at all. Not converting your cryptocurrencies back to fiat, and not storing them on an exchange will be the best way to dodge taxes. Pretty sure that if you hide your keys well enough, the IRS and co cannot prove that you have any assets in cryptocurrencies as long as how you acquired them can't be traced.