Glocks have evolved plenty; they have changed just about every part on the gun since it came out, some parts several times. If some trends continue, may have to evolve a bit more.
As far as a manual safety, what the "indefinitely postponed" JCP/CP said:
3.4.6. Safety:
3.4.6.1. DA/SA Pistols. The JCP in the DA/SA configuration shall have an internal safety mechanism that prevents the loaded cartridge from firing if the pistol is dropped or struck and mechanically prevents the firing pin/striker from contacting the cartridge primer unless the trigger is pulled (T). DA/SA pistols shall have a de-cocking lever that lowers the hammer from a cocked position and returns the pistol to DA mode when activated (T). The JCP design shall prevent the firing of a chambered cartridge when the hammer is cocked and the de-cocking lever is activated (T). The operator shall be capable of activating the de-cocking lever with the firing hand (T). The operator should be capable of activating the de-cocking lever without shifting the firing grip (O). If configured with external safety, the weapon shall meet the requirements of 3.4.6.1.1.
3.4.6.1.1. DA/SA Pistols with External Safety. The JCP in DA/SA mode with an external manual safety shall meet all the requirements of 3.4.6.1 with the addition of: The external manual safety shall prevent firing when the manual safety is applied and the trigger is pulled (T). The operator shall be capable of activating the external manual safety with the firing hand (T). The operator should be capable of activating the external manual safety without shifting the firing grip (O).
3.4.6.2. DAO Pistols. The JCP in DAO shall have an internal safety mechanism that prevents the loaded cartridge from firing if the pistol is dropped or struck and mechanically prevents the firing pin/striker from contacting the cartridge primer unless the trigger is pulled (T). If configured with an external safety, the pistol shall meet the requirements of 3.4.6.2.1.
3.4.6.2.1. DAO Pistols with External Safety. The JCP in DAO with an external safety shall meet the requirements of 3.4.6.2 with the addition of: The external safety shall prevent firing when applied and the trigger is pulled (T). When configured with an external safety, the operator shall be capable of activating and deactivating the external safety with the firing hand (T), and should be capable of activating and deactivating the external safety without shifting the firing grip (O).
So... maybe 3.4.6.1.1 and 3.4.6.2.1 don't apply to the MHS since they didn't mention it this time? The trigger safety on the Glock/XD/M&P, the grip safety on the XD are enough?
Hey, they considered the single action striker fired action of the XD a DA/SA pistol for contract purposes in the JCP/CP!?
51. Item 3.4.1 Action. Will all Striker Fired Actions be considered Double Action Only regardless of what the striker does during the action of pulling the trigger? Is there any Double Action definition as to what makes it a DA or DA pull? How will Double Action be defined?
Answer: The specification will be changed to state: DA/SA is defined as an action that sets and releases the sear with the first pull of the trigger, with subsequent shots being single action, only releasing the sear from a preset position, to fire the weapon. DAO/ Striker Fire is defined as an action that sets and released the sear with every pull of the trigger. Note: Any Striker Fire action that fully sets the sear will be considered DA/SA.