The Sessions Memo: What Changed Today and What Did Not

The recent emergence of the state-legal cannabis industry in the US has been explosive and a cause for optimism on several themes:

Health: Patients of all ages from young children to athletes, military veterans and the elderly use cannabis for relief from a variety of debilitating conditions, without the addiction and overdose risks of opioids, and with no recorded overdose deaths.
State Economy: Legal states have experienced $Billions in sales, $Billions in annual tax revenues, hundreds of thousands of jobs, new small businesses filling underutilized real estate, diversified agriculture, and technological advances.
Public Safety: The total US cannabis industry is estimated at ~$50 Billion. By 2020, the regulated state-legal industry revenues are estimated to be ~$20B – a 40% reduction of harmful activities of cartels/street dealer using market forces.
Popular sentiment: 64% approve of recreational use (Gallup poll) and 94% approve of medicinal use (Quinnipiac University poll)
Adult Use: Adults in state legal markets now enjoy cannabis recreationally without the deadly risks of alcohol or harder drugs
Financial opportunity: investment opportunities
... and more.

What happened today?

US Attorney General Jeff Sessions rescinded the Ogden Memo (2009), The Cole Memos (2011, 2013, and 2014), and the Wilkinson Memo, all of which recommended a moderation in using federal funds for enforcing cannabis laws in states where such enforcement could be better handled by local law enforcement.
"... today's memo on federal marijuana enforcement simply directs all U.S. Attorneys to use previously established prosecutorial principles that provide them all the necessary tools to disrupt criminal organizations, tackle the growing drug crisis, and thwart violent crime across our country."

What has changed?

The Sessions Memo (a 1-page memo is shown on the Justice Department website, though one wonders when further detail will be available) opens the door to federal prosecutors to pursue investigations.

What has not changed?

AG Sessions antipathy toward cannabis was well know: the Sessions action today was never an “if”, it was always a “when”. However, the US Congress makes laws and the Justice Department enforces them. Congress still has the opportunity to change the way cannabis is handled at the federal level, including removing it from Schedule I of the List of Controlled Substances
State officials where voters have legalized cannabis have come out strongly in support of the industry:
Colorado Governor John Hickenlooper said: “Thirty states comprising more than two thirds of the American people have legalized marijuana in some form. The Cole memo got it right and was foundational in guiding states’ efforts to regulate the production and distribution of marijuana,” Hickenlooper said in a statement. “Colorado has created a comprehensive regulatory system committed to supporting the will of our voters. We constantly evaluate and seek to strengthen our approach to regulation and enforcement. Our focus will continue to be the public health and public safety of our citizens. We are expanding efforts to eliminate the black market and keep marijuana out of the hands of minors and criminals. Today’s decision does not alter the strength of our resolve in those areas, nor does it change my constitutional responsibilities.”
Oregon Governor Kate Brown "...defended the state's efforts to curb illegal activity under its recreational and medical cannabis programs, and touted 19,000 jobs and $100 million in revenue she says the state has benefitted from. Should the program be threatened, Brown said she and Attorney General Ellen Rosenblum are prepared to pursue "all legal options available to us."
US Attorney for Oregon General Billy Williams said his office will "will continue working with our federal, state, local and tribal law enforcement partners to pursue shared public safety objectives, with an emphasis on stemming the overproduction of marijuana and the diversion of marijuana out of state, dismantling criminal organizations and thwarting violent crime in our communities.”
The Rohrabacher-Blumenauer Amendment is still in force. This amendment to the spending bill for the U.S Justice Department prohibits the DOJ from using any of its budget/resources to interfere with or prosecute State-legal medical marijuana businesses
Federal law enforcement was always able to prosecute crimes such as selling to minors, distributing across state lines, or supporting cartels
Financial challenges such as All Cash, over-taxation (IRS 280E), and no cross-border commerce remain
No Uniform standards (dosages, medical training, testing)
Because of the above, investing in cannabis has always included risk, esp. plant-touching businesses. Investing in cannabis-ancillary businesses have always been lower-risk