Yes it can be saved! Get out the duct tape and bandage up the trunk by pressing the cambium or inner bark layers back together so they can fuse into the same meeting spot before the big split. You may need to wind the duct tape around the trunk like you would affix a splint to a leg. I have had coral bark maple trees split like this and my neighbor also had a large Japanese maples split and we both had success using duct tape. After a year or two you can remove the tape. If the gray color is a bit much you can find duct tape in brown and even a camouflage print. Grow for it, Marianne Binetti