One thing I know for sure, in Malboro at least, I have not seen a single /tell or /shout. /says are still present however.
Curiously, I have noticed a potential pattern with these advertisements in /say from many hours doing homework while logged in to chat with friends or waiting on a timer. Every so often, the character advertising in /say will rotate out with another one. I do not know the timing/duration, or even if this amount of time is consistent for that matter, but it sure feels pretty consistent. Despite being probably obvious, anyone care to confirm/actually time them?