It's hard to tell what will happen to the current negotiations over the FTA. Whatever the outcome, these are the last days of the negotiations. A deal needs to be made by the end of March. The Korean government says that rice negotiations will be the clincher but I've heard from many (from both industry and social movements) that a last minute deal there is possible. There are some other issues as well that could be deal stoppers, but I'm not too optimistic. Anyways, let's just wait and see.
Sunday's protest on the other hand was quite surprising. One, because the police allowed it -- mostly because of the negative publicity they received after beating up reporters and bystanders on March 10th, and perhaps because even some URI members attended this time. The march was also able to march into Gwanghwamun unobstructed, which was even more of a surprise. The picture below shows you a considerable crowd, of both protesters and police, amassed near Gwanghwamun and the US Embassy (thanks, Matt).