If it becomes legal and if the big companies offer a product that the majority of smokers would approve of (I'm not sure how well that product would be received to be honest). Surely there would still be a strong market in connoisseur/high end products (all organic for example). Plus, I'm sure there would be markets for specialist hash, extracts, charas, CBD products, vape (etc) that smaller growers could focus on. If it became legal in the UK I'm sure they might follow a similar example to Holland. So perhaps selling direct to coffee shops is a possibility. Or maybe setting up small conglomerates or organise grow unions (with coffee shop outlets).
Ok, so we don't know what way it will be offered (if legalised) but surely there would be strong specialist markets that would offer profit for focused small time growers (or unions of growers).
I have a dream!