I can assure you that it will go back up.
Its confirmed by many people that gold dropped by mobs are significantly reduced since patch 1.04.

I heard from an avid botter that nobody bot for gold anymore but for legendary and p-level.
That, combined with nerfed gold drop, will surely impact the gold somehow.
Just my 2 posen, but rare gears not selling for squat might also contribute to gold demand later on.
rare not selling+less gold drop>occasional sucky legendary>casual fag turns to buy gold>demand goes higher.

For now maybe the slump of gold price is attributed by low demand+impatient gold sellers wanted to meet their profit.

I could be(very) wrong, though.The plevel might actually boosted the gold botters even with nerfed gold drop rate?
Just shooting in the dark from what small intellect I have.