Doge will collapse sometime in the next year.
This is because the mining subsidy is being halved, several more times, and each time that happens, in the presence of cryptocurrencies that are providing relatively stable mining subsidies, it's going to cost doge about half its mining effort.
At a point about six months from now, it will merit (on the basis of mining profitability) less hashing power than several other altcoins with market capitalization less than one percent of its own.
Unfortunately, it needs security (hashing power) in proportion to its market capitalization. When its hashing power drops as low as that of another altcoin, it becomes as easy a target for an attack as that other altcoin; but because of its higher market cap the attack on Doge will be proportionally far more profitable.
So the attack will be launched, eventually; some major chunks of coin will get double spent, scammers will make a ton of money off attacking the coin, and then (once the scammers have spent theirs) everybody else will get a chance to revise its value downward to no more than the remaining mining effort can secure.
I'm annoyed with Spoetnik for starting this topic without pointing out the technical reason why Dogecoin will fail. His idea of "bad" is purely hyperbole and without basis in fact. I agree with him that Dogecoin is in fact bad, but he is supporting the idea with damnably weak arguments and in a way that antagonizes people, rather than by pointing out the facts of why it is (like most fast-mined alts) guaranteed to fail.
That is a fair criticism.
However, there are ways that this problem could be solved.
- The value could increase. The demand is strong enough to eat 180 million new dogecoins, most of them mined and dumped by multipools, everyday. If that demand remains, it is likely that the price will increase when there will be under 10 times less new doges produced everyday.
- The developpers have mentionned a few times that if the hashrate becomes problematic in the next halvings, dogecoin could switch to PoS. This might happen after the initial 100 billion coins have been mined.
- Other coins could become merge-minable with Dogecoins. A dogecoin pool recently implemented merge-mining with Pesetacoin, and other coin developpers have said that they are considering it; like Digicoin if I'm not mistaken, and there's also Tacocoin. And the idea of being merge-minable with Litecoin is not out of the question.
- There's "charitable" mining. Many dogecoin users have expressed their willingness to mine at a loss to protect the network. There's an initiative on a subreddit called DogecoinDefenseForce, and they have been pledged about 1 gh/s that will always mine doge even at a loss. And it's not the only one.
- Litecoin's price could drop, and thus all the altcoins would share it's massive hashrate. The smaller coins would have quite less security problems.
It seems probable that at least one of these scenarios will happen and thus the network will stay secured.