I'm not sure 861 and 862 have come that far....other than, perhaps, to source income to the location of where the services were rendered.

On the other hand, 61 'all income from whatever source derived' has a tendency to look to the taxpayer (receiving the income) rather than where they received it from....unless there is a residency / permanent establishment issue under the treaty.

I'm not sure the digital world will change that too much...pillar 2(?)...but I'm no expert.