The solution to S-300/S-400 is simple - saturation attacks using low cost, high altitude cruise missiles. Fly them too high to be intercepted by AA guns, with a payload too large/powerful to ignore, and the S-300/S-400 would be forced to expend a hugely expensive missile to intercept. Continue sending the wave until all missile are expended, then let your planes attack.
The biggest problem is likely to find a military contractor willing to build an inexpensive high flying drone.
The biggest problem is likely to find a military contractor willing to build an inexpensive high flying drone.