The companies that have to worry about the Kindle Fire are other Android-based tablet-makers. They are in real trouble at this point because they’ve already shown they can’t compete on the high-end with the iPad and now I don’t think they’ll be able to compete on the low-end with the Kindle Fire.
I don’t see where there is any room left in the market for other tablet-makers. I doubt it’s possible to build a decent tablet for less than $199 and Amazon and Apple dominate every price point above $200. Acer, Archos, Samsung, and Motorola must be worried, very worried.