What do you think? Do you think forum is losing userbase and this is a bad thing? Are there other reasons this is happening and other solutions?
I think that it may also be related to the fact that lately (6-12 months, at least) [it should be seen as an addition to your list]
* bitcointalk seems to be punished by search engines, it's getting much more difficult to find anything here
* competitor forum(s) have come to life, some automatically paying per post (I know that it attracts mostly shitposters, but.. what if it's not only shitposters? I can't tell for sure though.)
And yes, the fact that we don't have a proper (default) mobile theme looks to me too as a big problem.