I don't think the release of new forum software will increase the Bitcointalk user base because;
The new forum version or software we are expecting will not in anyway increase the number of quality or problem solving posts in the forum. It is the forum users that does that. Ever presence of quality posts keep old users and attract new users.
The new forum version will take care of the user friendliness of the forum, which is expected of every upgrade of a system. Therefore, it is only when someone is aware of something that a change will increase or decrease the user base.

I am of the opinion that the fund for new forum should be diverted to increase the visibility of this forum in the search engines. Such that whenever anyone searches any keyword about cryptocurrency, this forum appears. By this, the number of users will increase.

Another factor is the reason people join Bitcointalk. If someone joins because of some monetary benefits, once the person makes the money he is out. It is therefore necessary for the forum to breed and sustain users that are here primary for knowledge gaining and sharing. By this in 10yrs time, we could actually see what to look back at and smile.
Thanks!