If we take bid sum (the quantity of USD on the orderbooks waiting to buy BTC), ask sum (the amount of BTC on the orderbooks waiting to be sold), and bid/ask ratio in exchanges as an indicator of money sitting in exchanges, we can have an idea of the demand for BTC around the world.
Sure the two (bid sum and actual money sitting on exchanges) are not necessarily the same thing, but history shows that they can reliably predict uptrends.
Let's start with Chinese exchanges Huobi and BTC CHINA (since chinese exchanges move the market more than any other exchanges who just blindly follows them most of the time).
Huobi
The picture speaks for itself, bid sum decreases over time.
There something particularly interesting to note though.
Look at the decline that we have had that bottomed out at $275. Price was going down but the bid sum was slowly increasing.
Chinese buyers were waiting for that target and in fact we saw a short term recovery that lasted quite a while with a ridiculous bulltrap that topped at $475 before resuming the crash.
The same is NOT happening right now.
Sure price is pumping right now. But could just be a bounce pump after a flash crash, classic stuff, exactly like we had all year.
No new fiat money to support a healthy and prolonged uptrend.
BTC CHINA:
BTC CHINA shows a clear constant decline of demand.
The exchange is not really being abandoned, because there is a lot of coins to be dumped, but not fiat coming in.
Bitfinex doesn't show any particular difference over time, that is probably because of the fact that it is used mostly for margin trading and because of the maker-taker system. Still, we are not gonna observe any increase in demand here obviously.
BTC-E shows the same picture of BTCCHINA, demand slowly drying up but the exchange has lots of coins to be dumped.
Now Bitstamp. As you can see, the decline in bid sum is clear, but wait. What is that sudden increase we can see lately?
The bid/ask ratio has gone up, but that doesn't necessarily mean that the bid sum has gone up... Let's see more precisely what happened there.
As you can see, the bid/ask ratio has gone up, but the bid sum has stayed the same, no new money.
What happened is that the ask side has dried up right after the Bitstamp HACK.
My guess is that, because is a lot easier and quicker to withdraw BTC than it is to withdraw fiat, a lot of people have simply decided to GTFO of bitstamp after the hack.
Still, no new money, demand is not increasing.
Conclusions:
If we take bid sum and bid/ask ratio as indicators of new money flowing in exchanges, we can see that demand has been slowly and gradually decreasing in all exchanges since the peak of the bubble. Some exchanges show signs of 0 new money coming in but plenty of coins on sale on the orderbooks.
A healthy and sustainable uptrend needs constant fiat money being poured in exchanges, as we have seen with the previous bubbles.
Without real demand, any uptrend will be short lived. Price will not magically go up to $500-$1000 or in a new bubble as most are dreaming here.
) will dump because they will se lack of strength. Exactly as it happened with the rally that we had in 2014 that topped at $680 in the middle of the bear market. It was a "fake" recovery with mostly margin longs and low volume, no real actual money flowing in. That's why it failed and price crashed again. 
