As much as I want this to be a thing, there are several issues.
1. The text will get too small to read
2. If we are allowed to zoom out, the window will be broken which causes the top three things to rescale itself such that the "gear" settings will be on the far right. This is just solving a problem with another problem.
As far as I can see, the only real solution would be to design a forum page especially for mobile users but this itself is troublesome cause different gadgets have different screen sizes and thus every different platform needs an entirely new forum page.
Still, this mobile forum page would be thin enough such that mobile users won't have to scroll an infinity left and right. Even if it's not a perfect fit, it's better than the desktop which isn't optimized for mobile.