This forum is tedious to use on a smartphone (there's no mobile theme, font size is too small, you have to use landscape mode + zoom). How come nobody has mentioned it? Theymos could fund some devs to improve the forum.
While having having forum better optimized for mobile phones would definitely be a good thing, I don't think that if would reduce decline at all.
Most cryptocurrency folks prefer to use FB groups for discussion these days... I'm not saying you're going to find quality discussions there. It is what it is.
Maybe 7-8 years ago, but not anymore. At least that is my experience as majorify of those that I've been part of are in the even worse state that this forum. Nowadays, Twitter is the place to be as everything important in crypto gets published there first.