I actually just blogged about this topic recently:
http://geekysweetie.com/youtube-gaming-live-streaming-service-compete-twitch-tv-sign-early-access/
My understanding is that content will exist in both youtube.com and gaming.youtube.com
The difference is that when a user browses gaming.youtube.com the following will happen:
All non-gaming related search results will be removed. The example youtube gave was if you type in "Call" you'll only see Call of Duty, not Call me Maybe
Gamers will be able to add a game to their "collection" whatever that is? And upon doing so they will receive updates about new videos posted for a specific game. Good way to track news, trailers, gameplay footage etc for upcoming games if you ask me.
Live-stream content will be "front and center" (probably have the majority of the front page) Alongside this they will also still offer game trailers and lets plays.
You will no longer need to schedule a live event in advance which is the current way live stream works on youtube. Instead you can stream at any time much like you can on twitch.
---------------------------
There are some draw backs though. As I mention in my blog article, from the feedback I've seen in the gaming community thus far I've noticed the following:
"The problem is that Twitch already has a huge following of gamers, both those streaming their screens, and those who wish to watch others playing the games.
Youtube has also been victim to false DMCA claims lately which has the community concerned in how music from their gaming streams would be handled in the new gaming streaming service."