In less than a month, Canada will become only the second country in the world and the first G-7 nation to bring marijuana prohibition to an end, legalizing cannabis for recreational use.

The move comes at a time when major corporations such as Constellation Brands are deepening investments in the space, cannabis stocks are seeing major volatility, and talk of a bubble is brewing.

Canadian legalization, jump-started by Prime Minister Justin Trudeau's government some three years ago, also has broad implications not only across the country but for its neighbor the U.S., where the drug remains illegal at the federal level. The Oct.17 deadline brings with it a slew of unknowns, including how large the market for cannabis in Canada will be and whether there will be enough product on store shelves. Estimates have run the gamut from $4 billion to $10 billion in the first few years of implementation.

Some analysts think the move may pressure the United States to accelerate legalization in some capacity, as states continue to take matters into their own hands by legalizing locally.

"We are sitting back now and watching the Canadians take market share with regards to international export opportunity," says Matt Karnes, founder of industry analyst firm GreenWave Advisors. He cited deals such as Constellation Brands' recent increased $4 billion stake in Canopy Growth Corp. and reports of Coca-Cola's interest in CBD, which has pain relief properties but doesn't get users high. "And multinational companies that are stepping in, or potentially want to step in, are all eyeing Canada, whereas I believe the United States clearly has the most robust and compelling opportunity for cannabis."

Right now 30 states and Washington, D.C., have legalized for medicinal use, and nine states and D.C. have legalized for recreational use, with GreenWave projecting a market of nearly $13 billion in the U.S. in 2019. Midterm ballot initiatives to watch include recreational measures in Michigan and North Dakota, Karnes says, and legislative measures expected this year in New Jersey and early next year in New York.