coinbase pro and coinbase prime customers receive a 1099-K if they pass the 200 transaction/$20k threshold. once you pass the threshold, they will place a restriction on your account and formally require you to complete a taxpayer ID request.
Thanks for sharing that.
Related interesting stuff:
a crpyto audit letter from the IRS requesting a ridiculous number of things for 2017. Someone posted it on Reddit without any details (some claim the letter is fake). Would be interesting to know if the poster was caught by the 200tx/$20k threshold.