People making house-calls selling knives is also still a thing, but I wouldn't recommend getting into that business. The business existing doesn't mean it is a smart business to get into.
The high-availability-doctor/one-stop-shop variety of weed business relies on loose medical laws but draconian recreational laws. Recreational users don't want to shop around for a doctor to approve their "condition", so these businesses do very well for themselves. Legalization, combined with regulation of medical, will remove a large segment of these businesses target audience.
Some people seem to think I am saying that medical marijuana will go away. I am not. I am just saying that these "convenience businesses" cater primarily to recreational users in markets with draconian recreational laws. Those people are their bread and butter.
Do you think that Florida's infamous "pill farm clinics" would still do well if you could buy Vicodin over the counter in 7-11's? Doctors would still be prescribing Vicodin because it is a useful medication, but would those businesses that specialize in getting prescriptions for middle-class addicts stay in business?