It's interesting question! the GND pin was there for a reason. The fist thing I know is the chip will have degrade performance. In CMOS we need path to VCC for the pull up and GND for pull down. If one of the ground pin was disconnect, the pull down resistance will be higher and it wook make a lower transition on falling edge. In general, the propagiation delay will be longer.. It may not affect if your design is working in a very low frequency than the chip's spec, but in general, it will give you a failure