Many of the problems associated with the tobacco industry aren't as likely to come up in a legal cannabis industry. If anything, I'd think a cannabis industry would look more like the alcohol industry than the tobacco industry.

For one thing, cannabis is much easier to cultivate than tobacco, so the issue of there being a prohibitive cost + very few growers would hopefully be avoided in a legal cannabis industry.

Chemicals being added to cigarettes has happened for many reasons, but a major one has been smoothness of smoking, as tobacco is fairly acrid on its own, and cigarettes oftentimes sit on shelves for a long time before they are opened/smoked. Cannabis users overcome potential harshness associated with smoking this through water pipes, using extracts, eating things with THC in them, vaping, etc.

So I would see a more similar potential structure in terms of industry with the current alcohol industry (although hopefully they would never implement the ridiculous 3 tiered system that current exists in alcohol), wherein there will undoubtedly be national brands that offer competitive prices for a consistent product (in booze this'd be your Budweiser/Miller, or Jack Daniels/Smirnoff etc), and then there will be local producers who will make more designer consumer products (similar to craft breweries and craft distilleries).

Also, cannabis is as easy to grow (if not easier) as beer is to brew. Given the growing popularity of home brewing, I see no reason why in a future of legalized cannabis there wouldn't be a reasonably popular home-growing movement.

Also, cannabis strains, like alcohol variants, share key similarities, chemically, but vary considerably in terms of the way they actually effect you. So, as opposed to being a "Marlboro Man" or a "Camel Guy", cannabis users, like alcohol drinkers, may well associate types of cannabis with different experiences/social circumstances.

That's what I think, at least.