That's a fascinating question about the future of industrial automation! You're right to imagine that with Industrial IoT (IIoT), we're moving toward a world where PLCs could indeed become much smarter about their own health.

The concept you're describing is essentially predictive maintenance taken to its logical conclusion. Today's IIoT systems already enable remote monitoring and data collection, and we're seeing early forms of predictive analytics that can forecast equipment failures. The next step would be automated systems that not only predict failures but also initiate maintenance actions - including ordering replacement parts.

However, the cybersecurity implications are significant and quite concerning:

1. Supply chain attacks: If a PLC can order its own parts, attackers could manipulate the system to order malicious components or disrupt legitimate supply chains.

2. False failure signals: Hackers could trigger unnecessary maintenance, causing production downtime and financial losses.

3. Financial fraud: Automated ordering systems could be exploited to create fraudulent purchase orders.

4. Physical safety risks: Compromised predictive maintenance systems could prevent legitimate maintenance, leading to equipment damage or safety hazards.

The reality is that many industrial systems today still lack basic security measures like authentication and encryption. Before we get to fully autonomous self-healing PLCs, we'll need much stronger security foundations - things like zero-trust frameworks, secure remote access protocols, and continuous monitoring systems.

What do you think - would you trust a PLC to order its own replacement parts, or would you want human oversight in that process?