Are you saying that companies can't bought other companies and take ownership of their patents?
But at least, a patent troll would have to buy an entire corporation rather than just its patent portfolio. Kodak, again: if let us say Toshiba wants Kodak's imaging patents, they'd have to buy Kodak in its entirety. At least this would raise the bar to acquiring patents.
Another issue I see is that patent trolls could just represent patent owners in litigation and charge high legal fees (or sign a contract that they receive all revenue for the patent).