I don't think that Itachi was "good" or "evil" - he merely had his own goals and folowed them and, by what I saw in the last chapter, it looks like those goals were killing Madara. Ofcorse, if could be something completely different - we can't say untill we see it, and I bet it will either something no one thought of, or something so obvious, that everyone thought of, but never considered it could actually happen. Anyway, we'll find out in a couple of days anyway