I'd love a proper hiking camera bag. Fitted semi ridgid waist strap to put a lot of the weight on my hips, mesh back, a full sized tripod strap on the side, monopod strap on the other. loops top and bottom to take extras, dedicated pouch for 1 litre bottles of water/juice. Compartment for waterproofs, waterproof cover large enough to also cover the tripod, rip stop fabric, longer and not quite as wide as current backpacks. Clip on to waist strap for ND filters. Spare battery compartment.
And I'd like a day tripper version, still with monopod/full size tripod straps, just big enough to carry a 600mm f4L mounted to a body and a wide lens, batteries and waterproofs.