Globals can now issue sig bans so it'll happen more often but isn't going to be a let off for everyone (so if half your posts are copy and pastes then forget about it but people who are getting banned for one or two posts from years ago will likely be shown some mercy).
It depends on how many times of plagiarism. If markiz73 only did it one or two times so far, especially did it years ago; and had good net effects, markiz73 surely will be considered and likely given a mercy, and can jump out from the grave. Above is stance of hilariousandco, that is clearly states that second chancce is not a common one for all permanent banned users due to plagiarism. As global mod wrote, each appeal will be considered carefully, by looking and finding past plagiarism, not only what already reported, but also global mod need time to dig deeply and find potential more plagiarism before making decision on a second chance. Past contributions and good net effects are clearly shown by supporters, so it is only takes time to find out more past plagiarism, I guess.