AFAIK, similar regulations have existed in many countries, US included, for quite a while, and to date I know of no one personally who had the border control agent demand to look into their laptop/phone.
I also don't quite understand why you necessarily have to change all your passwords. Nothing in the article had any supporting evidence that you are required to hand over your passwords.
If it is just the officer asking for you to unlock the device so they can look at the contents (in your presence), that's one thing. If they demand that you hand them over the passwords, and let them take the device into a back room and do whatever they want with it, that's another thing. It all depends on how they actually want to enforce these regulations.
The bottom line is - a border control officer has a lot of power to deny you entry for whatever reason, and your refusal to hand over your device for inspection is just another such reason. If they apply it too broadly or too stupidly, they will be shooting themselves in the foot, because if you harass visitors, they stop coming, and that's bad for them.
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