If bitcoin is the first cryptocurrency to be accepted by the market, then bitcoin will continue to dominate that market even if some technically superior solution comes along. How many people here have seen a betamax vcr?
That's a huge leap and a poor analogy. Being first mover in a market often means nothing more than providing seed ideas for a more powerful player.
Betamax did not 'beget' VHS. Betamax was a competing standard that came to market about a year after VHS was introduced. The Betamax standard and level of video quality was superior in many ways, but it lost the race for one simple reason. It wasn't better *enough* to overcome the 'first to market' advantage, and now they are lost to history. In order for any new cryptocoin system to overtake Bitcoin once the market is established would require either a dramatic improvement in usefullness (unlikely) or a near monopoly level form of institutional support. A cryptocurrency established and supported by the Federal Reserve, as an example, could probably crush Bitcoin at this point and for a long time into the future within the confines of the US legal system. However, it would still have to compete with Bitcoin internationally on it's own merits. The success or failure of one system or the other would depend greatly upon the future faith of foreigners.
I'm not saying it's impossible for another system to overtake Bitcoins, but assuming that Bitcoin can make it for the next couple years unchallenged, it's going to take quite an advantage for another system to win.