Gulden has dropped position from the low 40s to mid 50s on coinmarketcap. Other coins have performed better in price but not in real value as Gulden has added more development where other coins have done nothing.
This can only be attributed to a loss in community. Slack is not a replacement for a forum as I cant browse the discussions taking place. Lots of "guest" users read the forums that don't worry about registering but want to see what is being discussed.
I think that is oversimplifying a bit, to name a few factors I can think of and by no means an exhaustive list:
1) We had an unfortunate (albeit temporary) setback with the iOS wallet and Apple - some investors will be waiting to see the end result here before they commit further, if iOS was important to them.
2) We then had, as you will know, a huge prolonged public fight (over an embarrassingly silly thing) including a reckless and large sell wall and some crazy pump action, this sort of thing does not inspire confidence and it will take some time for the damage of this to be reversed.
3) We then suffered an attack, which while we responded quickly to it is again going to leave some people somewhat demoralised for now.
4) Due to the above our Bittrex wallet was offline for a few days, which again will make traders nervous for a while until they return, especially the cautious ones who aren't following closely what actually goes on with the coin.
5) This coincides also with a slightly 'dry' period for releases/news - which will soon come to an end but is unfortunately timed with all the other things above and also as the dev team had to concentrate on the attack our latest release has been delayed a bit.
6) Then BTC is on the up which makes some people want to hold BTC rather and/or potentially cash out
7) Finally it is the end of the year, which means that people will be spending money on gifts for their loved ones, holidays, and other things, meaning less money to speculate on NLG with.
All of these things and more will be combining right now, and have left everyone a bit tired and demoralised, yet despite that
the price actually has held relatively steady. This is actually a good thing.
Over time more news will roll in, great new releases will come out, the forum drama and attacks will become a distant memory, we will enter the new with a renewed energy and carry on forward.
The high BTC price also makes it much easier for coins with very high supply to 'manipulate' there 'market cap' on coinmarketcap - coinmarketcap remains in my opinion one of the absolutely worst indicators to compare currencies based on.
Regarding slack I don't see anyone claiming it is a replacement for forums, they are different, yes they compete to an extent (they are both communication tools) but they do not have a 100% overlap.
Slack is real time, which allows for faster communication, it allows for better bonding, it is a much better place to actually get to know people, form bonds, create friends or partnerships. You will find people casually talking about stuff on Slack that you would never see come up on a forum. It is as a result also a great incubator for ideas and projects and for spontaneous teams to form for these projects. The realtime nature causes people to be themselves and more honest because there is less time to think about replies. People can get instant help. etc. etc.
At the same time forums are also great, they allow much more thought and much slower communication, so they are a good place to have discussions that require lots of thought, they are also a great place for news to go, where people who only check by occasionally can catch up with goings on. To have the sort of discussion that takes place on slack take place on a forum actually undermines the usefulness of a forum, we have over 14k messages in a single week on slack. Imagine coming once a month to check up on a forum and there are 50k messages, where to even begin? (Yes the topics help to an extent but not entirely)
In short they both serve a purpose, at the end of the day people will use what they are comfortable with, and nobody can force them not too, we cannot force people onto the forums just so that people who only read forums do not feel left out, just as we are not forcing anyone onto Slack.
For now there has been a large swing to Slack as clearly it is what people currently prefer (and also because it is new), but I am sure over time and as the project grows, you will see the forums also picking up again, the two will work together to form a better synergy than either can provide alone. And hopefully other mediums like Reddit/Facebook and whatnot will also play a role.
Malcolm hit the nail on the head right here.
