First of all, welcome back [MENTION=26711]ico[/MENTION].
I agree that Telegram and Whatsapp have shifted traffic and random discussions. But I think its not a main 'cause' of actual decline of forum traffic. It was eventual.
Time have shifted to instant messaging, instant gratification and 'groups', where a few but regular and sometimes known people talk about anything under the sun and without the strict moderation that a forum has. Reddit is also a thing many prefers now and could the 'blame' be attributed to.
Anyway, yes but the first thing that this forum need is restructuring of forum sections, already discussed in mod zone long ago. I believe though, a sudden complete overhaul of the existing structure can very well be detrimental and thus changes should be discussed thoroughly before implementation.
Migration to Xenforo is another thing, and I don't know its impact, since there are no major bugs in this vB based forum anymore. A glossy UI may be the need of migration tho, but I believe 'value' is decided by a forum's discussion/members rather than looks. Many forum members prefers a simple but functional forum, rather than a glossy but confusing/complicated user interface.
I think digit magazine have started introducing its readers to forum more diligently now and I think its working too. Since we are getting new members, but I don't think retention period is any good, so they quit before they start.
Next thing to work upon to increase traffic is to allow/encourage users to share stuff. We can also have more section moderators who would like to post new threads and start a discussion. And by encouraging users I do man some kind of incentive system, rep or rewards. (No mater how much I personally dislike it).
