If you are mailed to 1099k form you can claim zero profit and be done with it.
What is interesting is that this new rule also has a requirement for the payment app to collect the users EIN or SS#.
This part is still being flushed out but expect this sometime.
I would also expect that this recording and collecting will be used for state sales tax collation as some sites do not include this.
If you buy on Ebay or Amazon you automatically are charged your local state sales tax.