Tirek does not get Discord's magic. Unexpectedly, neither does Discord. Instead, it heads off to a new host, one currently lacking her usual magic and in dire need of some. Why her? Who knows! Discord doesn't, but that doesn't mean he doesn't like what he sees.
Celestia is now Equestria's local reality warping creature of Chaos. And she's rather good at it. Thankfully, she's still the Celestia they all know and love. So, as long as her friends and family give her a little nudge whenever she gets a little too crazy, things should work out fine. Right?