This is the same argument that the proponents of peak oil put forth. Discovered uranium deposits != all uranium deposits on earth. When price pressure is put on uranium, we'll have more speculators looking for it. (Which the article addresses.)

Also, Economically unaccessible today != economically unaccessible tomorrow. Our mining technology gets better all the time, especially if there's price pressure on it. We're accessing deep-sea oil deposits that we weren't able to twenty years ago. (Which the article addresses, but you omitted the key point!!! We have a 60,000 year supply of uranium in the oceans!)

The chief problem with coal isn't pitmining, it's the pollution from burning the stuff.