Mayor Michael Bloomberg likes to talk about the big picture, even if it might not be pretty. Yesterday, he warned New Yorkers how their city could suffer by 2030 without his plans for the future. With a million new people coming into town, housing needs would soar. The sky could be as gray and toxic as London in the '50s. Every road into Manhattan would be above capacity - a gridlock nightmare that would make today's traffic jams look tame.