Would Bitcoin ever become centralized? That's a huge fear in any mind.

But I think there will always be lots of miners, just that they'll continue to use more powerful hardware until they can no longer mine using that hardware, then continually upgrade. They would do this to support the network, and to protect their own interests - which is the face value of bitcoins. In the face of increasing hardware costs, bitcoins would need to rise to help meet the financing of the hardware upgrade cycle.

I can't see how this could cause great harm to Bitcoin, but it's possible down the road...just that I can't see how it could if everyone keeps increasing their hashing power.