Many people think that bitcoin is unbeatable because it is soooo "big".  Let's remember though that bitcoin is a payment system, and right now of any market it effectively has a "0%" market share.  Visa and Mastercard do more in 5 minutes than bitcoin does in a year.  So yeah, there is still a lot of time and room for another coin to be established in the future, challenge, and then smash bitcoin.  It has a big start, but if a truly revolutionary alternative comes around that is faster, safer, more efficient and has more versatility, well...... Has any coin done that yet?  Not even close, most are just cheap clones of bitcoin saying they are doing the above, but not really doing it.  Is it faster? 10 minutes to 1 minute?  Okay, yes, but not that big of a deal.  Higher encryption??? Has bitcoins encryption been an issue?  More efficient??  NxT does address the issues of waster computer power and electricity, but is that going to be enough?  More options?  Lots of coins say they are going to implement more options, but has this really changed the game?  Not really.  Still...... again, if a code comes around that is faster, safer, more efficient and more versatile and it manages to capture even 0.1% of financial transactions, it will still be magnitudes larger than bitcoin, and much more powerful.