Just Part of the Job
The fact that Microsoft posts life cycles and retirement dates for its products is commendable, and should serve as a reminder that planning software purchasing cycles, upgrades and new development is an essential part of an IT manager's job. Let that slip off your priority list, and you're taking an unnecessary risk.
And there's more to it than just checking your vendors' Web sites from time to time. You have to develop good working relationships with vendors so you know what's on their agendas. You have to continually evaluate new products, ideally in your own environment, so you know the options should you need to make a change. And you have to coordinate with your business office so you have the budget to pay for new applications, upgrades and developers' time.
I've heard more than my share of horror stories about applications that no one wants to touch for fear they'll crumble. Often these applications have been running for ages, and they keep running as long as no one messes with the configuration or reboots the server.