Two different issues I think:
1. Is cyber warfare a real threat? My bet is yes. And every year, it probably gets to be a bigger potential problem as more and more infrastructure becomes dependent on online communications. Is no one worried about what will happen to smart grids and such if our inspired and dedicated leaders manage to get into a serious pissing contest with clever opponents? That's a rhetorical question. The answer seems to be "No. What's to worry about? What could possibly go wrong?"
2. Can tanks be replaced with autonomous weapons? I should think so. The problem I foresee isn't capability. It's that battlespace communications have always been notoriously iffy. I don't think replacing static-laden voice links with multimegabyte per second digital links is likely to improve things any.
Biting the hand that feeds IT
