The only mainstream browser that doesn't support TLSv1 by default is IE6, and it's been dead for quite some time.
(At one of my API endpoints, I'm seeing IE6 market share in the range of 0.013%. And this is in South Korea where IE market share is abnormally high to begin with, so I'm sure the numbers are even lower in most other parts of the world.)
So this change has more to do with API clients than browsers. Unfortunately, a lot of API clients are still written for, and run on, grossly outdated platforms. For example, Java 1.4 is as old as IE6, but one still sees it in the wild from time to time.
(At one of my API endpoints, I'm seeing IE6 market share in the range of 0.013%. And this is in South Korea where IE market share is abnormally high to begin with, so I'm sure the numbers are even lower in most other parts of the world.)
So this change has more to do with API clients than browsers. Unfortunately, a lot of API clients are still written for, and run on, grossly outdated platforms. For example, Java 1.4 is as old as IE6, but one still sees it in the wild from time to time.