With all its Abilities S 400 is a Weapon Created by Man and its a really really Good Weapon but it also has its limitations , Terrain will have its affect i m not sure about Sardodha , and Badin but Lahore is plane so it will have much better visibility unlike Islamabad
Regarding Swarm of Cruse missiles and drones , Currently Pakistan doesn't have that much inventory of specific drones for that task , Yes it could be created and it will help alot in War time
As these Small , Long range drones can much Larger Area really quickly and if they are able to Stay Up in Air for long Duration can work as Satellite and keep providing update to date Info on specific target or Area
one thing Indian Army will Try to keep its Weapon Safe where these Can be Covered By other Systems as well as can provide cover with Man and Air Force
Current Limitation is Battery as for longer endurance and capability you need you need more battery and bigger air frame even its not a Plane but it still be tracked with modern Radars before they really cause problem
For Swarm Like actions
one thing could be created Smaller Drones with large numbers attack ( Work as Cluster Bomb ) a enemy with specific task to disable the Enemy instead of totally destroying it but for that you can use Military Vehicles need to go closer to enemy as these drones with current Battery as i said limitations of battery and inventory unless Pakistan builds 1000s Than it will be only applicable in true sense that each target gets attacked by 100 smaller drones it wont have the ability of big but devastation will be on much larger area
Unless Pakistan has thousands of Cruise missiles liying in stock that Swarm wont work as these System can target and engage 20 to 40 Targets at same time if PAF tries to attack with 5 or 10 80 % it wont Work
Example of True Drone Swarm now imagine if you send these