Well, first we need a much wider Bitcoin adoption... IMHO alternative cryptocurrencies are just for the "community", to test new features and come up with possible improvements for some "new" (read: widely-adopted) cryptocurrency (or become one).
For me, the value of YAC is its innovation.
And have any of these alt coins managed to achieve such improvements? Unfortunatley, no. Their technological achievements are negligible - mostly stabs at shorter transaction times and (in vain) preventing concentrated mining efforts by using different hashing algorithms.
Once all YACoin have been mined, it will be functionally identical to LTC, FTC and BTC for that matter. The only exception is the faster transaction time, which comes at the expense of security.
Like it or not, speculators are driving the Bitcoin market forward. This is a truly free market after all. And as there's no effective way of short-selling Bitcoin, all they can do is force the price to rise.
I don't understand what you mean. Don't miners sell their BTC for USD? This will drive the price down. You can also short sell Bitcoin by selling futures contracts on sites like icbit.se.
But apart from that I disagree that Bitcoin is being driven by speculators. BTC is a widely accepted form of currency, and it has a thriving market. There are very things that cannot be purchased with BTC, unlike the alts which have no commercial support whatsoever. Frankly I don't see why they should have.
- Michael