Scotty has said it before, the V8 will slowly become a thing of the past with increasing fuel mileage minimums for vehicles. 

Nothing confirmed yet. Lots of rumors. Some say turbo 6, some say 6+hybrid, some say 8 will still be an option.  I strongly doubt they will offer only a v8, like the current Tundra, simply due to fuel mileage.  I suppose the question is whether Toyota wants to primarily serve their existing customer base (sell just the one motor they think is best; probably a hybrid 6) or try to take market share from the big-3 (which will require multiple options).  

I don’t think you will have to wait too long to find out; dealer update should be released by early March and press release soon after. 

Time will tell what will happen and how it will go...