Nah,as i far as concern,artillery is still the god of war (till the tank came rolling in)
1st,they are cheap,an a-10 thunderbolt cost 12 millions dollars while an m198 cost 600 thousands dollars,means that you can buy about 15 arties with trucks for towing and ammo for an a-10. 15 arties will surely do even better at bombarding enemies (albeit risk getting to closer range but still,15 guns correctly place is harder to destroy) And you don't need fuel,special care for arties.Just set them up and the next 5 minutes you gonna see all hell break loose while it may take nearly 20 mins to get an a-10 up and running for CAS
2nd aircraft are in greater risk of getting kill,we all know that it is not fun flying above Vietnamese flak system with Israeli pilots chasing us,things will be like the great mariana turkey shooting.Arties can be better protected,they can be dug in fortification and get out in a blink,they can be unloaded into many packs,they can be disguised and dispersed into many location,and unlike planes,they don't need special airfield or specifically trained crew to do the jobs.
3rd they are much more simple to maintain and to train someone with them.In case we decided to go total war with Chincom,it will be much easier to train thousands of mens and guns and send them into war:dbanana