I'd like to point out that, technically speaking, Arthur already revealed the existence of magic several months ago and with what POandora just did, the cat is well and truly out of the bag.

(Also, everyone at Moperville South knows that Nanase has magical powers--they've all seen her floating in the halls. Pisses off the physics teacher something fierce. It's surprising that Mamma Kitsune hasn't gotten a call about that.)

Arthur doesn't know it yet, but he can't cover this up even if magic changed radically.

At this point, a controlled reveal by the government on the ball the whole way, with a heavy emphasis on the good that magic can do, is probably the only way to go forward without major problems.(Which is not to say that there won't be minor problems, and some a-hole in the Government might try somekind of magical registration act which... if Comic Books have tought me anything, even with the best of intentions that never ends well.)

Or, in other words, the only way forward is for Tedd to get what she wants.