Well, diet sodas will be excluded. You can get as big a bucket as you like of diet soda although I imagine that it'll be less hassle for establishments to just have the 16 oz as the "new large" even for diet sodas. And under the law, you'll be welcome to get refills or as many sodas at a time as you like as long as each one is no more than 16 oz. Bloomberg claims he's just trying to "reset" people's ideas of what's normal. It is often hard in the States to find a truly small drink, often the smallest available is 16 oz or more. It is a little bit out of hand and Bloomberg has a point. It's a lot easier to drink a zillion calories of something without really processing it or feeling full. I just think the mayor is going about this in kind of a ridiculous way. I'm a very liberal person but I don't think that absolutely everything can be legislated.
A lot of people are comparing it to the smoking ban. I believe that New York (under Bloomberg) was one of the first jurisdictions to enact a ban and now it's pretty standard most places in the US and in Western Europe, I think. The difference of course it that there's no such thing as second-hand sugar. The (official, stated) goal of the smoking ban was to reduce second hand smoke exposure, especially by employees of bars and restaurants, since second hand smoke has been proven harmful. If it encouraged smokers to quit or cut back, all the better, but that wasn't the real reason for it.