Just to add on the coming big block rumor... It may not be a GM engine. Might be the psi 8.8L with di and variable timing. Which is is an newer version of the 8.1 GM sold to PSI. A version of the 8.8 is already in production and in use in school bus applications.
What I've heard is the big block won't come in any light duty truck. Strictly medium duty. The 6.6 is what we get for now. It's about as big as the gen 5 will take for bore, so stroking will be the only way they get bigger without a new design with a bigger bore spacing.
Then again this is a rumor and in 6 months to a year I might turn out to be all wet.
I like the sound of all that, except for only being offered in the medium duties. They need to at least allow it to be a motor option in the 3/4 ton and 1 ton trucks (sure the duramax can be the standard option, but if you pay a tiny extra you can get the BBC instead). I understand the new 6.6 gas has some good points to it, and will probably be a great motor in the normal 3/4 ton truck uses (towing your camper trailer for the weekend), but please say that GM doesn't screw it up and not offer that motor in the 3/4 and 1 ton trucks. Could you imagine a PSI 8.8l 540 cubic inch big block with forged bottom end and direct injection from the factory? Dang, that's something to take a second look at! And if they did the variable timing on it, I would think for sure you could get that thing to have mpg's in the teens in a 3/4 and 1 ton platform (though I'm still not sold on variable timing, I understand why their doing it to bump up mpg's in normal driving circumstances).
Here's to hoping I guess