Here is the thing we are overlooking. The darker side of the cloud being that a precedent has been set. There are bunch out there mistakenly relieved that they bought their BTC in 2016, 2017 etc. This is actually a big win for the IRS as they just got their foot in the door. That said everyone in the last two years that meets the criteria should likewise expect their information to be handed over at some point.
This time; however, Coinbase won't put up nearly as hard a fight, if at all as there is now a legal precedent and they no it is a losing battle. Also I think we have failed to estimate the ramifications if the initial Suspicions by the IRS are confirmed. We know they will be based upon the initial BTC user base, the ease of avoiding taxes during that time etc. Ergo the IRS will have a hell of a lot more foundation to their next request based on provable evasive tax information obtained in this initial lot of customers Coinbase will be handing over.
That in turn will allow them more power to start prying into all things Crypto.