How will banks influence thousands of people, who has a vested interest in keeping the value of Bitcoin to increase the cap and to run the new changes on the protocol? Nobody in their right mind would sabotage
their own investment like that. The problem with many of the Alt coins is, that their total Cap of coins is way to large to sustain a high price. If you look at these stats
http://coinmarketcap.com/ you could see
why some coins will never have a huge value per coin... There is simply too much of it availlable and it will never be rare enough to reach Bitcoin's price level.
A real competitor to Bitcoin will have a low amount of coins that would ever be released to increase it's value, with all the other things that influence it's demand.