Alright, I realize this is some SERIOUS nit-picking, but it's beginning to grate on my nerves;
The "next newest topic" would be, as I understand english grammar, LESS new than the topic you're at, and therefore actually OLDER. The "next oldest topic" would be LESS old than the topic you're at, and thus actually NEWER. In other words, the exact reverse of the way those links function!
"newer topic" and "older topic" would be both clear and gramatical. Don't go to any trouble to change these on my account, I just had to vent the accumulated irritation. However, if you encounter my Jr. High school grammar instructor, be VERY afraid!
Sic semper tyranus!