It's a fairly trivial change. We already have timezones, which exist to deal with the fact that the sun comes up at different times in different parts of the world. We already have to design everything around the assumption that timezones can change, since people sometimes move to different parts of the world. All we do is cause, for an entire timezone, that it becomes a different timezone at one point in the year, and switches back later. This ensures that the sun continues to come up at a consistent time. The main issue it causes is to make the lives of programmers slightly more difficult, which I am sure they can cope with...