I think there will be more bitcoin forks in the future like Namecoin or Ixcoin. The loyal miner will stay at bitcoin, but the greedy miner will try to exploit the difference in diffulties (and coins per block), assumed there is an exchange for trading in the other currencies into BTCs. Logically the price should be balanced at the ratio of the different difficulties (+blockcoins), if there is enough liquidity at the exchanges. I think we need some kind of chainhopper tools, or at least a page, where the current profitability for each pair are shown. I think this gets really interesting, if an IXC<=>NMC exchange starts, so there will be some triangle arbitrage opportunities... I hope
http://dot-bit.org/tools/nextDifficulty.php will upgrade soon ...