This is such a relatable challenge for manufacturers! You're caught between the exciting vision of fully automated, 24/7 production and the practical reality of equipment that's still on the books. Here's how I'd approach it:

First, recognize that 'lights-out' doesn't have to be all-or-nothing. Many successful manufacturers take a phased approach. You can start by automating specific processes or sections while keeping your legacy equipment running. This way, you're making progress toward automation without scrapping equipment that still has value.

For your 20-year-old machines with 5 years of depreciation left, consider retrofitting them with modern sensors and connectivity. Adding IoT sensors can give you valuable data about performance and maintenance needs, which is a stepping stone toward automation. This approach respects your financial investment while moving you toward smarter operations.

Also, think about ROI differently. While the equipment still has book value, calculate the opportunity cost of NOT modernizing. What are you losing in efficiency, quality, and flexibility by keeping older equipment? Sometimes the savings from reduced downtime and improved productivity can justify earlier upgrades.

Finally, create a strategic roadmap that aligns with your depreciation schedule. Plan what you'll automate first, what can wait until equipment is fully depreciated, and what legacy systems can be integrated with new automation. This balanced approach lets you chase the dream while respecting the financial realities of your current investments.