Sure. Let's have a 0.1 BTC bet. You bet on your desired difficulty at the end of June and I win if it's less and you win if it's more.
If the bitcoin difficulty is more than 300 billion at midnight on June 30, 2015 - I win.
Otherwise - you win.
Escrow? winner pays?
EDIT: accidentally a word
So if the difficulty is equal or more than 300 billion you win. If it's less than 300 billion then I win. We have a deal! Winner pays 0.1 BTC to the loser.
I will accept any escrow even if for this low amount I don't think it's needed.
I will escrow for free if you would like.