It wou'dn't make sense for me, but I'd be happy to see Toyota do it if they thought they could do a good job on this type of vehicle. AFIK, all the consumer hybrids so far are unibody-type, car or car-like vehicles.
For me, I don't drive enough to ever have it make sense. In-city mileage would probably go from 16-17 MPG to about 23-24 MPG. Highway mileage might not improve significantly.
And then there's the extra compelxity and potential for pricey repairs, even if the engineering is solid.
Hybrids are at their best for low-speed, stop & go driving. There have been some successful bus hybrids, and I keep waiting for things like delivery and garbage trucks (which are constantly burning fuel to burn up brakes) to go hybrid. That might be the best return on investment.