Isn't that exactly what people have said will be the case?
Frankly I don't trust the rabble when it comes to rumours. They're prone to blowing things out of proportion, latching onto claims despite evidence showing those claims to be false and generally assume everything is the "worst thing ever".
Bindi on the otherhand has actual information coming from the inside and while he doesn't share a lot (or perhaps get a lot to share) but he's rarely (if ever) wrong.
Furthermore we've seen from Iyanden that the supplement books don't invalidate anything in the codex, or add in new units or move things about the FOC, things you'd need to do to represent chapters like the White Scars.
My prediction is that we're going to get an updated version of what we have now, with less emphasis on Ultramarines (likely to help deflect fan backlash about them posterboying it up all the time), and a couple new toys (I'm going to doubt a flyer since they have two, but I could see a new big thing going in there).
Also on my list of things I expect:
- Dreadnoughts will have Powerfists not Dreadnought Close Combat Weapons
- Thunderhammer/Stormshield Terminators will likely go up in points vs the Lighting Claw variant
- Relics in the main book will be somewhat generic but the chapter specific ones will have more specialized ones
- Black Templars won't be in there (sorry, but it's only been claimed in speculation, but not by anyone who actually knows anything)
- Librarians will get points adjusted, but will have to roll for powers
- The power to force players to re-roll successful invulnerable saves will become a malediction.
- Calgar will automatically be your Warlord if you take him.
- People will bitch about how over/underpowered it is/isn't.
That about sums up what I expect for the new released, based from the releases so far. Not rumour, just speculation.