I watched yesterdays streams (The last Gbeastcast and Alex's drumming stream) and there was a lot to pick up on.
Abby is just doing Twitch for right now, but I think from what has been said from various people. it is clear what Giant Bomb will be moving forward.
First was Jeff's garage stream, where he talked about his wife being pregnant again, and how she has been having severe morning sickness. He has to move his office out of the house and into the garage. He also hinted to moving out of California. He said basically both offices got the axe, and that Jan had to go to the west office to retrieve all of the equipment to give to the people. So there will be no more 'office' Giant Bomb.
Vinny said on the Beastcast that he was not given the tools to be successful at his job, so apparently there is some issue there. He also alluded to how difficult working from home is, and how that has put a lot of stress on his life.
Alex's drumming stream was interesting, because he played ride the lightning near the end of his playlist. He said after he left Gamespot, he played this song as one of his last videos there, "which was fitting because the feelings are the same today". It was clearly obvious Alex was upset, and alluded that leaving Giant Bomb was not mutual.
Interestingly enough, it looks like Jeff Bakalar has been consistently on both Abby Russell's and Dan Ryckert's twitch streams. He is now one the two people in charge at Giant Bomb, along with Jeff Gerstmann. So my guess is Giant Bomb is changing to a twitch like service, where there will be a lot of content makers that will have some sort of deal with Giant Bomb.
I think Dan and Abby will probably be announced as Giant Bomb

Official Twitch Partners, and their streams will be hosted on Giant Bomb and will likely make exclusive stuff, but they will be independent and do their own thing. So I guess Giant Bomb is pretty much going to be like machinima or curse.
My speculation is Vinny, Alex, and Brad were basically told the premise of new Giant Bomb and did not like knowing the rest of their careers there would be spent behind a webcam. I think they know that can do bigger and better things than being glorified twitch streamers.
Abby is still young and probably wants to continue a career in games media, and Dan likes streaming for fun, so they probably both will take these offers with open arms. The rest probably felt like its time to move on. All of them mentioned moving out of the areas they are in. San Francisco and New York sound like hell to me so I don't blame them.