They keep it around, but I've noticed recently I just randomly get opted back into the new design. When I go to settings to opt back out, it shows that I'm already opted out. Then I just click it, which going by the button state would opt me in, but it opts me back out again. It's weird, and it seems clear that they're just auto opting me in on the back end and hoping I'll just deal with it, which I can't because the new design is impossible to navigate.