I think this needs more detail as to what stage in the tech lifecycle the businesses are in. Obviously, I'm going to trust an electricity company to provide my

I think this needs more detail as to what stage in the tech lifecycle the businesses are in. Obviously, I'm going to trust an electricity company to provide my business with electricity. I'm even going to trust laptop manufacturers to continue to provide laptops I can code on. In both those cases, the thing I'm depending on is a commodity, where there is also either strong competition or regulation. There isn't much risk in depending on them. The stage to be wary of is when a whole industry is still at product stage and people are trying to move them into being platforms, or using them to Innovate/Leverage/Commoditise (ILC, see Simon Wardley) to play ecosystem games. i.e. Where the business models and how the industry will be vertically and horizontally sliced are not yet settled. Those are the ones you should be wary of dependence on.