There is one threat that is the 'Daddy' of them all and it is really bad news. The Russian S-400 Triumf (NATO code SA-21 Growler). It can reach out to 400km, up to about 30km high (185km on Wiki for specific missile), down to about 5m and travelling at 5,000 m/s (MACH 15). It is highly resistant to jamming. It is extremely mobile, can be setup quickly and with only three personnel. It fires four different missiles for various range engagements and can engage 80 targets simultaneously
I don't know anything about the S400 apart from what I read here or wiki, but there is a clue in the quote. The ignorant assume that 400km and 5m are one corner of the flight envelope. The 4 different missiles suggest each missile is optimised for a specific part of the MEZ. So what is new compared with earlier, Nike/Hawk/Rapier layered defence? What is new compared with a 400km range missile retired by the US almost 50 years ago?
What is apparently new is the ability for a launch team to operate 4 different missiles. The ability to engage 80 targets simultaneously is awesome, but you also need 80 plus missiles plus reloads. Now the logistics must be awesome. Unless they are supplied wholesale as in Vietnam they could soon be shot out.
Impressive as the system undoubtedly is it will have wealnesses; I think logistics is one. Analysts will find a weakness somewhere that can be exploited.