Sure it will. The thing that I think Gates is missing is that even the poorest parts of the world aren't universally so. One need only think back to what it must have been like hundreds and even thousands of years ago. People back then were unimaginably poor by modern standards, how did we get from there to here? Incremental development a bit at a time. All it takes is a seed. A seed of literacy. And education, and entrepreneurship, and industry, and so forth. Once the norm starts changing things can reach a tipping point more rapidly than we tend to appreciate.

Look at South Korea, for example. In the 1950s they had been devastated by several wars (WWII and the Korean war). Today they are a wealthy industrial power house.

It may seem non-intuitive that today countries that are wracked by war, starvation, terrorism, corruption, and disease will end up with mass ownership of tablet computers over the next few decades, and that doing so will be one important facet in becoming wealthy, industrialized nations in the next few decades after that, but it's almost certainly going to happen.

Of course, spending a considerable amount of effort on curing malaria in the short-term is probably also a good idea regardless.