It's highly unlikely that a "next world war" would be fought mostly in cyberspace, in the sense of being entirely devoid of kinetic (physical) conflict.

However, it's virtually guaranteed that cyber warfare would be an integral, pervasive, and potentially decisive component of any large-scale future conflict between major powers.

Here's a breakdown of why:

Why "Mostly Cyber" is Unlikely (Pure Cyber War):

1. Limited Kinetic Effects (Directly): While cyberattacks can cause physical damage (e.g., Stuxnet's impact on Iranian centrifuges, attacks on power grids leading to outages), they don't yet possess the same direct, immediate, and overwhelming destructive power as conventional weapons (bombs, missiles, troops).

2. Attribution Challenges: The difficulty in definitively attributing cyberattacks makes large-scale cyber-only conflict risky. Without clear attribution, a state might hesitate to launch a full-blown cyber counter-offensive, fearing it could hit the wrong target or escalate uncontrollably.

3. Lack of "Holding Ground": Cyber warfare lacks the traditional concept of "holding territory" or achieving definitive military victory in the physical sense. Effects can be temporary, reversible, and targets can adapt or rebuild.

4. Desire for Decisive Outcome: States engaging in "world wars" typically seek decisive outcomes – the defeat of an adversary's will to fight, regime change, or significant geopolitical shifts. Pure cyber warfare might inflict immense pain but may not achieve these ultimate objectives on its own.

5. Unpredictability and Escalation Control: The cascading and unpredictable nature of cyberattacks makes it difficult to control escalation. A seemingly limited cyber attack could have unforeseen collateral damage or trigger a kinetic response, undermining the idea of a purely cyber conflict.

Why Cyber Warfare Would Be Central to Any Future Conflict:

1. Preparation of the Battlefield:

   • Pre-positioning: States are already conducting "hunt forward" operations and implanting malware or gaining persistent access to adversary critical infrastructure (power, water, finance, communications) to prepare for potential disruption in a future conflict.

   • Intelligence Gathering: Cyber espionage provides crucial intelligence on military capabilities, political intentions, and economic vulnerabilities, informing kinetic strategies.

2. Force Multiplier and Asymmetric Advantage:

   • Disrupting C2: Cyberattacks can cripple an adversary's command and control (C2) systems, making it difficult for them to coordinate their military forces.

   • Degrading Logistics: Disrupting transportation, supply chains, and energy infrastructure can severely hamper an adversary's ability to wage war.

   • Sensor and Weapon System Interference: Direct cyberattacks on military hardware, sensors, and weapon systems could degrade their effectiveness.

   • Asymmetry: For states with weaker conventional military forces, robust cyber capabilities offer an asymmetric means to deter or inflict costs on a stronger adversary.

3. Societal Disruption and Psychological Operations:

   • Civilian Impact: Attacks on critical civilian infrastructure (power, healthcare, banking) can cause widespread chaos, panic, and undermine public trust in the government, potentially breaking a nation's will to fight.

   • Disinformation and Propaganda: Cyber operations would be used extensively for information warfare, spreading disinformation, manipulating public opinion, and creating internal divisions within the adversary's society. This "cognitive warfare" aims to weaken morale and public support for the war effort.

4. Cost-Effectiveness and Deniability:

   • Lower Barrier to Entry: Cyber capabilities can be developed and deployed more cheaply than many advanced kinetic weapons.

   • Plausible Deniability: The inherent ambiguity of attribution in cyberspace allows states to conduct malicious activities while maintaining plausible deniability, making it harder for the victim to justify a conventional military response.

5. Integration into Multi-Domain Operations:

   • Modern military doctrines increasingly emphasize "multi-domain operations," where cyber, space, land, sea, and air operations are seamlessly integrated. Cyber would be used to enable, complement, or disrupt actions in other domains. For example, a cyberattack on air defense systems could precede an air strike.

Conclusion:

While a "World War Cyber" in isolation is improbable, the next major global conflict would almost certainly feature cyber warfare as a foundational and continuous element. It would precede, accompany, and potentially follow kinetic engagements, shaping the conflict's intensity, duration, and outcomes.

The effects of cyberattacks on critical infrastructure and society are so profound that they represent a new form of "kinetic" impact, even without traditional explosions. Therefore, it's more accurate to envision a "hybrid" or "multi-domain" world war, where cyber operations are an indispensable weapon, constantly interacting with and influencing traditional military campaigns and societal resilience.