long enough, you don't have to worry

Past 2020? Thanks.

It may happen, but don't count on Mozilla going beyond the Microsoft E-O-L date for Windows 7. In the past Mozilla did keep Firefox compatible long beyond the published Microsoft E-O-L date, but "stuff" happens coincidentally that make it difficult for Mozilla to do that all the time.

iirc, Windows 2000 was extended beyond the official E-O-L, but later on with Windows2000 the issue was with the Windows Visual C+ + Redistributable needing to be updated beyond the last version available for W2K. The Windows Visual C+ + Redistributable was changed for Win8.0 and worked fine with WinXP, but not W2K.

And more recently to get up to Firefox 52 with WinXP & Vista Mozilla has needed to retain an older server in-house to keep building the version for WinXP & Vista; and do those builds separate from for Win8.0 plus versions of Firefox. Double the work for small percentage of users on E-O-L operating systems; so the line was drawn at Firefox 52 & 52 ESR.

And the "date" of that happening was like a year after other major web browsers out there had already stopped supporting WinXP & Vista.

I imagine Windows 7 will still be supported for a good while after as long as how Mozilla builds Firefox for Windows 8 and 10 will still work for Windows 7.

If Releases from a point on could not support Win7. If need be then maybe a ESR version normally made for Enterprise users in mind may be a option for to have a version that gets security and allowed stability fixes much like WinXP/Vista users had with 52 ESR.

There are far more Windows 7 and 10 users using Firefox compared to 8/8.1 https://hardware.metrics.mozilla.com/#goto-os-and-architecture

I run Winows 7 Home Premium, but Firerfox does not recognize this, saying there is "no support for XP & VIsta" Is there a work-around?

Make sure you aren't running Firefox in WinXP (Service Pack 3) compatibility mode. You can check by right-clicking the Firefox desktop shortcut and open Properties then look in the Compatibility tab.

DavidBassPlayer said

I run Winows 7 Home Premium, but Firerfox does not recognize this, saying there is "no support for XP & VIsta" Is there a work-around?

Two possibilities. Either you have been running Firefox in Windows XP compatibility mode for some time or you have modified the useragent.

Could you turn off any compatibility settings on your Firefox shortcut?

To do that, find the icon you use the start Firefox, and either:

• Right-click a desktop shortcut, then click Properties
• Right-click a Firefox icon pinned to the Taskbar then right-click Mozilla Firefox, then click Properties

You should clear all the boxes on the Compatibility tab for best results (giant screenshot below).

Any difference the next time you start Firefox? (credits to jscher2000 for above part).

Or you have a modified useragent for some reason. See https://support.mozilla.org/en-US/kb/how-reset-default-user-agent-firefox

Note after you fix the useragent you should download the current Firefox 62.0 Release from www.mozilla.org/firefox/all as a Update will go from 52.9.0 ESr to 60.2.0 ESR instead.