The amount of activity over at BoardGameGeek continues to increase. Earlier this year they reached 2 million registered users (
link), after reaching 1 million just 4 years ago. The number of unique visitors monthly is currently over 5 million (
link) and continues to grow. That does also mean there are a lot of lurkers who haven't registered for membership but still use the site regularly.
The same trend is evident on the boardgames subreddit discussion forum at Reddit. This is seeing phenomenal growth - subscriber #1 million was on 2 November 2018 (
link) and subscriber #2 million was near the end of June 2019 (
link), so it has doubled in size in the last 8 months alone.
The number of subscribers on the playing cards subreddit discussion forum (
link) is also growing, and just hit 10,000 a few days ago (
link). This grows at a rate of 20-30 new members a day. Many of these are younger and enthusiastic collectors just getting into collecting playing cards, especially modern custom decks. But if you want to promote 52 Plus Joker and try to bring a new generation into the fold, it might be a good place to get involved, because I rarely ever see it mentioned. There's a lot of regular activity there, with people posting photos of their newest decks, and discussing what they are interested in.
I think you're right that the current generation is using social media much more, and Instagram and youtube in particular have a lot of influence. Specialized discussion forums seem to be losing traction in favour of more centralized hubs like Reddit, which is huge, and extremely popular. It's easier for people to sign up for a single site that covers all their hobbies and interests, rather than registering on individual sites for each separate hobby or interest. I frequent a few other playing card forums, including UnitedCardists and Theory11, and there's a reasonable amount of activity there as well, but not as much as on Reddit. I'll try to get to get some stats from UnitedCardists to see how that compares with PCF. I think that young people are less inclined to register for a site dedicated to a specific topic, because you have to be pretty immersed in the hobby to register for a site devoted specifically to it. On the other hand sites like BoardGameGeek.com are also going from strength to strength, but that's because boardgamers tend to be a pretty dedicated bunch who really dive in deep to their hobby, and strategy boardgaming generally has really grown enormously in the last two decades.