How will the forum feel? I probably don't know. Does the forum have feelings?
How will members react to that? I can only answer for myself.
What will be the positive outcome?
It will result in the forum being more boring than a lot of members have already pictured it to be due to a lack of high-paying campaigns. Some members are no longer as active and productive as they used to be.
The admin would have banned it long ago if the casinos were illegal and there had been a government restriction on places where they could advertise the platform.
The forum is the community, so with a huge number of participants in the casino campaign, there will be a drastic drop in activity. For me, I will continue to post out of habit. I have been doing this for ten years, and it is something you can get out of your system easily. I can only speak for myself; I don't know about the others.