Not true. I've heard 2018 from lots of sources, not just financial.
What sources?
Also, the effect of Alberta styming all depends on what the federal legislation looks like. It's quite possible the legislation will make it a penalty to purchase from unauthorized sources, and most likely will increase penalties on unauthorized sellers. So it will be 'legal', but not legal. And when it comes to purely recreational cannabis, Hitzig v Canada doesn't apply, so until further court litigation it will likely be perfectly legal to make it impossible to buy/sell something that is legal to posess.
Given how long the Health Accord negotiations took (and they ultimately failed, provinces started cutting their own deals), 2018 is a pipe dream. There's a chart I'm trying to dig up that shows the progress to 2019, but it will probably take the entirety of this year to get legislation passed. Trudeau is now saying summer, and Parliament takes a summer break. Blair's 'tour' (paid vacation so he can assure his cop and fire friends legalization is really prohibition lite) also has to conclude.
Conservative Senators like Linda Frum are already banging their drums, I would bet on them trying to amend it and send it back to the House, if nothing more than a filibuster. And there is really no guarantee that the independent senator caucus (for lack of a better term) will swing one way or another, they are small l liberals, but they may have differing opinions on what legalization should look like, if they support it.
Creating an entirely new supply chain (unless the LPC decides mail order only is just fine) is going to take time. And things to be actually legal vs 'legal' is going to take even longer.