A lot of people might hop across to stack overflow or reddit.
True, but if people will be posting there under different nicknames, a sense of community will be lost. We could be interacting with the same people that we interacted with on this forum and not know this.
the thing is what will happen to members network of friends on the forum who may not border in sharing personal contacts e.g email if one day the forum suddenly goes offline how do we link up with each other and keep the discussion going.
I never spoke with forum members outside of this forum and have no way of contacting any of them in that way, so if something would suddenly happen to this forum, it would likely mean I'll never share a conversation with all the people to whom I've been talking to all these years.