More than likely, it will be an underbarrel configuration. When we consider the PLA's new focus on weapon system modularity, more likely than not, they will either attach a UGL to the mounting points below the handguard or they will introduce an alternative handguard more suitable for the mounting of a UGL. For instance:
Of course a UGL on a rifle will always be more cumbersome than the standalone rifle. With people bringing up arguements that it will be suboptimal in CQB. And indeed it is a suboptimal solution, but the cost benefit of being a little less wieldy for the firepower and capability a grenadier can deliver to a squad is well worth it. The handguard of the DMR version (QBU 191?) would look quite suitable for such a UGL to be attached.
A separate GL is also a solution, but a UGL allows a soldier to bring the firepower of a grenade launcher to bear on the enemy almost immediately, without having to go through your bag to fish out a separate GL that is in itself too bulky to be stored in pouches on your vest.