What consequences? Decreases in overall drug use? Dramatic reduction in overdoses? More resources to deal with real crime and criminals? Hell, Portugal even saw a decrease in alcohol related issues.
Of course the main health issue obviously is inhaling smoke from hot, combusted material. However, the more high-test the weed, the less you actually need to smoke thus keeping any damage to a minimum. Proper use of a vaporizer will also alleviate some of that as well.
A study done some years ago comparing regular pot smokers and regular marijuana smokers also indicated that when pot smokers stop smoking, their lungs heal up faster and more fully.
Marijuana is not addictive. Well, not addictive in the normal drug addict sense. Of all the commonly used recreational drugs, including caffeine and nicotine, marijuana is the only one that doesn't stimulate dopamine production. There are no physical withdrawal symptoms when someone decides to give it a rest.
I smoked it quite a bit recreationally when I was much younger. And although I never flew while high (well I did, just not a plane), I eventually quit smoking it. Didn't miss it. Now I use it medicinally for the days I don't need any of my prescription pain meds (which are a fast track to liver and kidney damage) but still need something to help manage the pain. Although I do occasionally run across stuff that has more of an analgesic effect which is preferable to being buzzed out all day, especially if I have to leave the house for anything.