I wake up this morning and go to eat breakfast and get my morning fill of 40k news. Ming tells me about a 2+ invuln save upgrade to some new GK squads in their next dex. Other sites have spoiled some other spells and units. People bitch and complain online about new crazy things or amazing upgrades. Sure the new GK codex will have some crazy stuff but so has every other codex that has come out in 5th ed. None truly game breaking.
GW has done a great job with balance and point levels for most things. Sure you may have a 2+ invuln on some guys but I bet you they will be ~100 points for a basic guy and any special characters with it will probably be in the 300 point range and with how most of the recent changes have gone those chars will probably still be instant deathed.
Everything has a counter balance in the game. You can never say something is just op by their statline. Points and drawbacks are what really matter and nothing great is ever cheap.
On a side note if you have not seen the fuzzy pics of the new cybertron like suit for the GKs go find it! I am all for new cool models and things we havnt seen.
Just wait till things are actually printed before you pass judgment about if a codex is OP. More than likely it will be balanced or have counters. Any power gamer will find a way and adapt the the new cheese of the month that the net gamers will throw at them. Its like how I jumped onto the BA band wagon because of the internet chatter about how good they were. After their shine wore off they became just another good codex and not overpowered. I have had them for 8 months now and still have yet to finish them. I am still magnetizing models and I have started painting my first squad and finalizing the paint scheme.
Dont scream OP till the codex drops! Even then I bet you my orks will win out! hahah