First, as to tobacco products, if you work as a cashier at a store that handles cigarettes among hundreds of other items, you will not be DF'd. If on the other hand, you worked in a store that sold only tobacco products, you would have to quit or be DF'd.
That out of the way.
I can remember when VCRs (or the equivalent came out). It gave people access to all sorts of objectionable films and TV shows. There was concern then about owning VCRs and the dangers to Christians. The same concern was expressed about TV. But even the WTS recognizes some value from VCRs (since they produce videotapes) and the TV (since they produce PSAs). The same thinking will prevail with the Internet.
Will they DF? No, unless,
A lot of people will freely post their name and congregation name. After all, what do they have to fear from Jehover's Loving Channel on Earth(TM)? The WTS then writes to the local body of elders who then "ask" the person to stop the activities. If the person refuses, then they will be DFed for "interfering with Jehover's arrangement".
I don't see anything newer that the WTS will be using. Outright forbidding is impossible unless people are going to be required to get jobs that have no access to the Internet. In this world, that is getting harder and harder.
Blondie