Might never go back to $30.
And you might get hit by a meteor while you're laying on the ground convulsing after getting hit by a lightning while you were celebrating winning the lottery.
There's nothing wrong with gw4tt's answer. Sorry if you're not satisfied by his answer, but his answer is 100% correct ...
You're asking for "the earliest, the latest, the average, and the best guess date when it says Bitcoin will reach 30 bucks again right now" ?
earliest guess date: today, in a few hours
latest guess date: unfortunately, never
average guess date: some time in the future
best guess date: /
Yes, I'm trolling around. But my point is: How should anyone in here be able to predict the future ? You just can't do that.
If you want the $/BTC ratio to reach 30, I can tell you how to do that. Just deposit $100,000 in a trading market with a very low volume and buy all offered Bitcoins up to 30 $/BTC. Et voilà ... job done.