OS and Hardware Lifecycle/Roadmap

Mac HW and Software is proliferated throughout Enterprise organizations, including where I work.

Other Enterprise HW and SW see the value in communicating to these orgs, their plans such as 1) when will "this software" be End Of Life, 2) when will this HW no longer be supported, etc... to a degree that you can roadmap the predicted EOL for all of their products, even current releases.

So far, we only know that Mavericks will no longer receive patches, and that MacOS Sierra has higher HW requirements than past OSs.

My question is (and I have looked for it)...

Does Apple communicate when they predict they will stop patching Yosemite, El Capitan or Sierra?

I know Apple is a "consumer-focused" business model, but dang it, the products are used in Enterprise too, and I have to try and build a roadmap and plan when we will need to buy new HW over the next 2-5 years!!