Yesterday I spent some time learning about this. Afaict, no smartphone manufacturer needs to lock down the bootloader for good, per se.
But consumers will have many disadvantages if they choose to unlock. There will be no warranty, no manufacturer support, certain kind of apps will get blocked, because the devs need to do so in order to comply with these new laws. Affected are apps of essential services like banking and healthcare, ect. However, webapps/websites are not affected really. It’s like a backdoor 
That’s how I understand it. Let me know if I got anything wrong.
I think this will cause a massive amount of e-waste, because whenever the manufacturer support of a device ends, many apps won’t work anymore as soon as one uses a custom ROM or has outdated firmware. I hate this law passionately!
I also wonder if this will encourage hackers to find exploits in order to spoof a “manufacturer supported device” to make things work again. I feel like this could cause even more malware floating around the internet. But not sure, just some thoughts. Maybe I got it all wrong