Traditionally artillery shells (155mm as discussed in the article) have a maximum effective range of 30km. That means that the artillery vehicle can only function within 30km of the front line.

Drones have dramatically changed this equation. The current drone "kill zone", which used to be several km from the front line, is now 15-25km deep, and Ukraine is pushing this to 50-100km. That means artillery cannot operate without being targeted by FPV drones. It is also becoming logistically difficult to supply the large number of artillery shells needed without getting struck.

Once the kill-zone reaches 30km, which it will by 2027, artillery will be completely useless.