Black MarketI don't think the black market will matter much 3-4 years into legal sales. When you look at booze and smokes in Canada, it's a cash cow for the Government regardless of the hicup they had with smokes awhile back.
Fact is, billions are made each year on these two items with no worries from the black market due in part by huge fines and jail time for offenders. Once the arrests start being made with real jail time and fines kicking in, black market will be tiny.
That's why it so important for the big players to gobble up all they can before licence restrictions kick in. The "players", once established, will call on the government to restrict new licencing due to market saturation and utimately protecting their industry from newcomers and importers of cheaper product.
Same bottle of wine I buy in Canada that costs $19 I can buy in USA for $9. Applies to loads of other stuff too, so why would you think it would be different with cannabis?