There would need to be lots of new laws about DUI, testing, employment, lawsuits for employers who still test for pot use, and so on. Plus taxes taxes taxes.
Worst part is, instead of DEA busting you for possession, now BATFE goes after “bootleggers” who dare to posess or sell homegrown or other out-of-federal-control weeds.
“...lawsuits for employers who still test for pot use...”
Some employers won’t let people work for them if they smoke cigarettes, even if they smoke while not on the clock. Employees have sued companies over these policies and lost. I bet if marijuana was legal there would still be many employers who test for marijuana and who will not hire or retain pot smokers.