Philosophy is generally two things. Firstly its speculation that leads either to fruitful endevors (such as natural philosophy, which then leads into science, or say logic or ethics or moral philosophy etc) upon which case it ceases to be the lead in those areas as the specialised fields become desciplines in their own right (as they should) or such speculative thinking goes nowhere (more often then not).
Secondly, once a field has established itself it becomes more about analysis.
So philosophy really is what you do before you've worked out how to do it or even if you should. Dennett (a quite well known philosopher right now) said something along the lines of "Philosophy is when you don't know what questions to ask".
The dimishing importance of philosophy is a good thing, it means that we're moving forward and getting better answers. Its quite ironic that the ultimate triumph of philosophy would be living in a world where its almost completely gone.
I wouldn't throw it completely out the window, there are some very clear thinkers that come out of the field (Such as Dennett, Grayling etc) and many horrible ones, mainly theologians in my opinion.
