I agree with you. Numbers of DS falling and it seems like even almighty Zynga cannot fix it.
Shameless plug: couple months ago I built an "adult" version that got little traction but nothing significant, and since I am not a marketing wiz, but a simple programmer, it ended up here: https://flippa.com/2765466
(http://www.marketwatch.com/investing/stock/znga/financials/b...)