Don't group all altcoins together. Altcoins really just means 'all of crypto except bitcoin'. There is a huge variety of alts, some are legitimate some are not. For new coins there is always a risk that it is a scam, so this is why researching before you jump in is vitally important. We must always be alert to keep ourselves safe from the scammers.

ETH is the best smart contract platform, it has a solid dev team and a real and achievable roadmap. Constantinople will mark another step along the route. ETH in the long-term should be very successful. Short-term I don't think it will fall more than other coins - but obviously everything is still falling.

Because markets are thin, which means that current buy and sell prices fluctuate.
Also because most coins are measured against BTC and ETH, so even if a coin has no trading, if ETH falls vs $, then that coin stays the same against ETH, and so also falls vs $.
Also because crypto is highly speculative, every coin offers a future use-case, which differs from the traditional non-crypto markets in which companies often have tangible assets and existing finished products.

I wouldn't be concerned. XRP has a very strong use-case, and crypto marketcaps and prices are volatile anyway. XRP remains one of the best coins. I don't think we'll see a price crash based on questionable circulating supply.

I really can't see NEO surpassing ETH in cap in the near future. Maybe at some point a few years from now it could happen, but at the moment ETH is streets ahead of the competition amongst the smart contract platforms. Some competitors do offer a lot of promise, and some may even be technically better, but ETH has a huge first-mover advantage.

I think everything at the moment is moving in response to the overall bear market. Even good projects struggle to gain any price. For a realistic assessment of what the price may become, I think we'd need to wait until the bear market is over and we start to see some rises.

I think ETH will recover against both dollar and BTC. Whether Constantinople can provide the impetus for an upwards move I don't know. Probably not. But when BTC rises start then the recovery of all crypto should start, and I'd expect an ETH rally to follow.

I think 2019 will be about whether and how much BTC recovers, and then any good alts will be dragged up with it.Some individual projects may do better than others, but I think BTC is the main price driver for alts, at least until the bear market is behind us.

I would say ETH and XRP. I know it's boring because tey're high cap, but still both look undervalued vs BTC.
Having said that, BTC often leads any recovery, so their price in BTC may drop further from current levels if the market starts to turn.

Some are predicting the death of crypto, but I think this is shortsighted. I think crypto still has just as much potential as ever, and it will become mainstream. As I see it this is inevitable. The only question is when prices will recover. I think this year we should stabilise and start to rise again. There was quite a lot of stability towards the back-end of 2018, until it broke. But I expect we'll be stable in the next few months at most.

I disagree that in 3 years crypto will be dead. It still has just a viable proposition as ever, as just as much potential. I believe crypto will become mainstream just because it is better, faster and cheaper than current tech. Businesses and consumers will always follow the better option. Yes the market is volatile, but it's not hopeless at all.

I think we'll see a new bull run this year. Maybe not up to 2017 heights, but I would say more than double current prices is certainly achievable. For huge rises we probably need institutional investment, which is probably tied to SEC and ETF.

At the moment it is difficult to see the bear market ending - but it will, and we will start to recover again. I would say the coin to watch is BTC because often it is BTC that stops falling first and leads a market recovery. It is also important to look at longer term trends rather than just daily or weekly charts - big percentage price movements at current prices are actually small in dollar terms relative to prices at the end of 2017, and so can be misleading.

ETH is a very strong project with a great future. I would normally say yes, buy ETH... but the state of the markets at the moment means it is difficult to advise someone to buy anything until prices start to recover.

It's not looking great in the short-term, but I am still confident that we will break out of this bear market this year, and return to prices increases. New ATHs seem unlikely though. If we do start to get up to big prices, everyone will be wary of another big crash.

I suppose a dead coin would mean no dev activity and no trading. What we really want to ignore is effectively dead coins, i.e. with very little dev activity or trading - and obviously this is a grey area, and so that's why it's harder to track.

One thing I'm quite confident of is that BTC is the coin to watch. Often in the past it has been BTC that has led any rally, with alts following later. Similarly if you look at when the big dip started, you can see that BTC had peaked and was already falling whilst the alts were still rising. BTC is often a good indicator of how alt prices will move.

If we think about the potential that crypto has for use in the real-world, we can see that this potential hasn't diminished in the last year... it still has the same potential it had at the 2017 ATHs. Prices are volatile, yes, but we shouldn't despair at a lengthy downturn, just as we shouldn't take a big upturn as evidence that crypto has arrived in the mainstream... that is still years away.
I do expect prices to rise in 2019 as I think they've fallen too far in this dip, but then I also expect further dips and rises in future.

I do think that we will eventually have full KYC for crypto and that it will all be checked properly. The situation at the moment, and how easy it is to fake it, does really demonstrate that even real legitimate ICOs who want KYC info often just do so as a box-ticking exercise in order to comply with the rules.

It's a very healthy attitude, and much better to think in this way than to have blind optimism.
The answer is that no-one knows. In hindsight if I'd realised the 2018 drop would have been as deep as it was, then I'd have sold more earlier... but I kept thinking it would recover.
So are we near the bottom now? If you think yes, then hold, if you think no then sell. We can take advice from everywhere, but fundamentally we are all guessing.
I think we need to keep one eye on BTC price. This is likely to lead any recovery.