Each fork / spinoff detracts very slightly from the immediate value of Bitcoin, I think... There's capital that could go into BTC that suddenly has another option. But it's a very small crowd that is aware of the ramifications of these spinoffs, and there's next to no comparative brand recognition. BTC will hold the largest interest & mindshare for quite some time. There hasn't been a fork yet that's detracted in any significant way from BTC, I don't expect that trend to be broken anytime soon.