Today upon visiting Bittrex, I saw that there are USD trading pairs.

You can trade these into USD: Bitcoin, Tether and TrueUSD.

Instantly what came to my mind, that this may end the altcoin dependance on Bitcoin. I consider this a really big step towards that.

Personally, I would welcome this, as I'm pretty bored of the altcoins following BTC's trend. Even if some big names criticise Bitcoin, but not any other coin, makes the whole market drop, while only Bitcoin should. This may change easily, and I'm hoping for it.
As I see it, Bitcoin is technically outdated, and I see no point of it other than everything trades into it.

I found some source if you want to dig a little deeper:
https://www.cryptoground.com/a/bittrex-usd-trading-pairs