On January 13, Microsoft's mainstream support for Windows 7 Service Pack (SP) 1 ends.
Nobody panic. This does not mean Microsoft is going to stop issuing security fixes for Windows 7 SP1 tomorrow. Or anytime soon, for that matter, unlike some of its competitors (cough, Google, cough).
"Mainstream support" is the period during which Microsoft provides for free security and non-security updates and telephone support for its products. "Extended support" -- the period during which Microsoft continues to provide for free security updates for products -- doesn't end until January 14, 2020 for Windows 7 SP1.
This support milestone for Windows 7 SP1 does not have implications for downgrade rights. Users will still able to buy a new PC with an OEM license for a business edition of Windows and then install an earlier version. PCs with Windows 8.1 Pro can be downgraded to Windows 7 Professional or Windows Vista Business. Microsoft volume licensees don't have to worry about their OEM's downgrade rights provisions; they have the right to downgrade to any prior version of Windows.
The January 13 deadline also has nothing to do with the end of sales cut-off date for PCs running Windows 7 Pro. Microsoft still has not provided a date as to when Windows 7 Pro will no longer be shipped to retailers or OEMs. Company officials have said they will provide one year of notice prior to that end-of-sale date.