For a modest unreported profit, assuming you converted it back to USD at an exchange that reports to the IRS, you'll probably get a CP2000 in the mail many year

For a modest unreported profit, assuming you converted it back to USD at an exchange that reports to the IRS, you'll probably get a CP2000 in the mail many years later with your recalculated back taxes (probably assuming a $0 cost basis that you'll have to provide records to dispute) + interest.