That's correct. But I am sure that many can be careful enough to keep his coins in multiple wallets and even if they make payments, only a small part of his wallets will get revealed. Then I guess that mixers will keep coming up for those who want to "start fresh".
If change addresses are properly used, they will not be able to track all those addresses with good enough precision for linking them to actual persons.
And if change addresses are used properly, the agencies will have a lot of DB space spent for addresses used in 2 tx (one in, one out) and when we'll have proper adoption ... I don't want to see how will they handle their databases
I personally see that the way this will be going is, Bitcoin users going for optional privacy will be seen potentially
worse than Monero users. Here's why:
Imagine you've used Bitcoin pseudonymously for the last 5 years and nobody knows who you are. Suddenly, you make a transaction to some Amazon dropshipper accepting BTC and the government gets at some point the information that it was
you who paid for that. From that point on, your address will be known as " NeuroticFish"'s address.
One day, you decide to enter the privacy sphere by mixing your coins. The authorities know that it was you who did that, but you obviously had a reason to do so. Doesn't it seem more likely to get interrogated and into trouble as soon as you decide to
switch the privacy flip than it'd be to use Monero straight away from the start?