Seems like Toyota would not have to do much to convert the half ton into a 3/4 ton gasser. Dodge has the 5.7 gasser in their 3/4 ton. Obviously the game changer would be for Toyota to put a stout diesel in one.
Internationally Toyota use diesels and they are very popular...but they are smaller engines vs what we see in domestic 3/4 and 1 ton trucks here. More on par with what Dodge is putting in their 1/2 ton diesel.
I loved my Tundra and really wish they had a 3/4 ton diesel option...as I believe they would probably be the most reliable. Of course I can't afford new trucks now so even if they came out with one next year it would be about 3 or 4 years until I found a used one I could afford :)