According to Microsoft SQL 2014 SP2 loses Mainstream Support from Microsoft in July 2019. (https://support.microsoft.com/en-us/lifecycle/search/17645)
Many Sitecore environments utilize this version of SQL.
What has Sitecore said about this when previous versions of SQL lost mainstream support?
What are peoples thoughts the ramifications of this?
Is this an urgent item that should compel companies to upgrade, say to Sitecore 8.2 Upgrade 3+?
For an answer to your question you should contact Sitecore (or Sitecore Support) directly. (Also I believe it's 7 September, not July 9).
However, for some additinoal information that might help prepare: as we can see in the Product Support Lifecycle KB Sitecore 8.2 is in mainstream support until 31 December 2019. Looking at the Compatibility Guide we can see that Sitecore 9 does not support SQL Server 2014 (except when using the CMS-only offering).
You'll also notice that there's an extended support offering for both Sitecore (31 December 2022 for extended support, sustained support ends 31 December 2024) and SQL 2014 Service Pack 2 (7 September 2024).
