A fixed air defence system is vulnerable to attack from missiles and aircraft as the opening stanza of Desert Storm illustrated when the Iraqi IADS was destroyed in a single night. However mobile GBAD is harder to knock out because its mobility is its best defence.Off-tangent discussion for context — Part 1
1. In a high end war fighting scenario, to my simple mind, I would assume that the enemy can sanitise the air of attack helicopters or UAVs, by use of multi-layer air defences, which is why it is so important to retain fires capability by self propelled 155mm artillery, HIMARS, PrSM and the like. Increasingly, I think any 155mm L/39 even when it is self propelled is a little too short ranged. Self propelled 120mm mortars must also be supported by its own organic UAVs.
2. Long range strike can be used to takeout SAM layers, with F-35As or F-35Bs serving as additional ISR assets
The British Army are introducing Land Ceptor into service and it's a game changer for them.
On the battlefield this with SPAAG / MANPAD system would offer a good mobile GBAD that could prove challenging to an enemy.
I think the point to remember is that we really don't know what will really work and won't work in the next near peer conflict. Modelling and theory offers some guidance, but at the end of the day once the first shot is fired a lot of that is useless because the actual combat is different to that envisaged. WW2 showed that in copious quantities with many lessons having to be relearnt or learnt painfully and at sometimes great cost in blood and treasure. Hence I believe that we should not forget lessons from WW2 and Korea, by having good, multilayered, plentiful MGBAD for the ground forces. Such MGBAD should be able to keep pace with armoured and other fast paced forces.