I'd argue that Altcoins can definitely become a store of value regardless of Bitcoins network effect.

Check out http://ripple.com - they pretty much solve this problem, although its VERY beta. Expect really cool things from them in ~6 months.

Ripple is fiat agnostic and allows seamless conversion between currencies. This means I can buy something in Yen and you can receive payment in LTC. Amazing system if it gets up and running.