I'm bullish on blockchain technologies over the next decade or two, but we're gonna have to clean up for awhile.
My hope is that blockchain enthusiasts are taking their profits and using them to invest in building something better.
(There's also a lot to be said here about the hucksterism, shilling, get-rich-quick schemes, and an almost-fanatical belief in the power of a pure free market inherent in the BTC community from the beginning, but that's best left to another post)
Worse, the people buying in now aren't true believers. They are "investing" because they think it is easy money. These folks represent a larger percentage of the market cap and are also least likely to have confidence in bitcoin for it's utility. They also stand to lose the most because their buy in point was so much higher. (people who bought in at say $1000, are just losing profits)
A panic sell will happen at some point.
As Bitcoin becomes extremely mainstream, those who hodl Bitcoin with religious fervor are increasingly becoming a smaller minority. Eventually it’ll reach critical mass and there will be enough disloyal Bitcoin ownership to cause a panic at the first significant sign of selling.
Once the bubble burst then no one argues that they were in a bubble.
But apart from that I am not sure what the future of ETH or LTC will be. To me it seems some adaptations of ETH have a much clearer use-case and therefore are likely to raise a lot in value in the future. One of the ETH based coins that I really believe in is OmiseGo[0] (OMG) which will bring banking capabilities to many people that currently don't have a bank account.
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If I had to bet, there is still lots of upwards runway left, but at some point, it will come crashing down, the bad [companies][coins] will be worthless, and out of the ashes will rise a more sensible market with some of these [companies][coins] truly changing the world.