Urbn Leaf Dispensary in Bay Park on Jan. 1, 2018. / Photo by Vito Di StefanoCalifornia regulators had plenty of examples to learn from last year when they rushed to establish the world’s largest legal marijuana market. Despite some delays and confusion, they managed to put together a functioning system. But success over the next year, on both the state and local level, is far from certain. Eliminating the black market in San Diego — one of the selling points of Proposition 64 — won’t be easy.