Marijuana markets--States' rights?

The Trump administration has an ever more complicated relationship with the growing legalization of marijuana by American states (see previous posts). The Attorney General is an ardent opponent of these legalizations, and seeks to actively enforce the still-on-the-books federal bans  (marijuana is a Schedule I drug, like heroin, according to federal law).

However there are indications that President Trump may not support this any longer:
The Motley Fool (that's the name of a news outlet, not an administration figure) has the story:
President Trump Flip-Flopped on Marijuana, Again

"What's interesting about the marijuana industry is that, while Canada is leading the charge, it's the U.S. that could be the world's most lucrative market for weed -- if it were legal, that is. Despite an overwhelming number of respondents in U.S. surveys in favor of legalizing cannabis nationally, the federal government has remained steadfast in maintaining a Schedule I classification for pot.
...
"Attorney General Jeff Sessions is very much at the heart of marijuana's lack of progress at the federal level. As no fan of pot, Sessions has repeatedly attempted to thwart expansion at the state level. In May 2017, he sent letters to a few congressional colleagues requesting that the Rohrabacher-Farr Amendment be repealed. This amendment, passed with each and every federal spending proposal, is what disallows the Justice Department from using federal dollars to prosecute medical marijuana businesses. Sessions' request has repeatedly fallen on deaf ears in Washington.
...
Last week, after consulting with Sen. Cory Gardner (R-Colo.), President Trump came to an agreement to end any potential federal crackdown on legal cannabis industries in states that have legalized in some capacity."
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We'll see what this means, given that not everyone involved has a long attention span...