This is ridiculous 
Many governments for years have had indirect ways to trace your income whether you declare it or not. So, in this way I dont really see a big difference between good old cash that is traditionally used in the shadow economy/ black market. Whenever a person tries to evade payment of taxes, s/he will easily succeed in it. At least for some time But then the IRS and other authorities come into play. Remember Al Capone? Had he used btc, I believe the result would have been the same 
So, not to worry, btc just cannot create a hole in the cycle of economy.
It is a legit question that can across to the mind of any beginner. Many governments for years have had indirect ways to trace your income whether you declare it or not. So, in this way I dont really see a big difference between good old cash that is traditionally used in the shadow economy/ black market. Whenever a person tries to evade payment of taxes, s/he will easily succeed in it. At least for some time But then the IRS and other authorities come into play. Remember Al Capone? Had he used btc, I believe the result would have been the same So, not to worry, btc just cannot create a hole in the cycle of economy.From the (production), the next bloc who will created, to the possessor of the last fraction of bitcoin from this bloc. The Bitcoin across with so many events unknowns and unpredictable toward the "actual economy", and with gives that would act by so unpredictable and unknown way!
That's why earlier in the beginning ,(2012 ~ 2014-2015), we'd remarked governments and decidants moving in favor toward apprehend Bitcoin and integrate it (to the economic model).