Vine was shut down, but there was a successor service of sorts. Musical.ly or something similar to that, which the vine junkies who didn't flock to YouTube latched onto. It was based in Shanghai, but people getting MATI didn't have too much of a problem with it.
Bytedance's Douyin reached the same level of popularity as Vine did in its heyday, and that was just in China and amongst the Chinese diasporia. Bytedance figured they might as well gobble up the competitor, Musical.ly, and so they did.
Given that TikTok carried over features that were the main appeal for Musical.ly (lip syncing to copyrighted music), it didn't experience an exodus of users, as it offered what made both vine and musical.ly so popular. YouTube is only now trying to copy the trend with YouTube Shorts.