Remember that question, "how long is it going to take?." That question sometimes gets a response of, "it takes as it takes." Meaning, the officials from Malaysia and around the world need to do everything and anything until they find that plane. You would want the same response If it was your family or friends on that plane.
Malaysia should expand their search on the report that Malaysia Airlines Flight 370 kept flying for hours. They should continue to dig for information until they find out what the cause of the situation was. If this was a terrorism thing then they could still be out there plotting other things.
I do not believe it is necessary to expand the search given that recent news reports indicate that debris may in fact be a part of the missing plane. I believe we are jumping to conclusions too quickly. A downed plane is likely to sink, contents included. Widening the search could simply delay finding the wreckage.
Malaysia shouldn't be searching for the plane in the first place. Clearly, China has more resources that can be devoted to the search of the downed plane. Malaysian authorities should simply hand over jurisdiction of the search to an international team of experts. Finding anyone alive is unlikely at this point. However, the plane still needs to be found. China, India, Japan and the United States are probably better equipped to find the missing jetliner.