Microsoft this week reminded any recalcitrant SQL Server 2005 users that extended support for SQL Server 2005 ends on April 12 2016, giving organizations only a year to work out a suitable migration path to a later and greater version.
Why wait a year though!? As is usually the way with these end-of-life events for popular and stable tools, Microsoft sees it as a "big opportunity for installed base churn", and will do its best to entice all organizations still harboring musty old SQL Server 2005 instances in their darker crevices to brandish a broom and sweep them out. You'll get better performance; according to benchmarks SQL Server 2014 is 13 times faster than 2005! You'll get incredible new features! You may even decide to give these old applications a new lease of life in the cloud by migrating them to Azure SQL Database!
However, many of the old departmental applications that still run on SQL Server 2005 (27%), or even SQL Server 2000 (roughly 10%), are reasonably undemanding in terms of the features they require of their database. They are no longer being developed, they perform "well enough", and all the major kinks have long since been ironed out or worked around, and so they have no real need to receive support from Microsoft. In short, the motivation to upgrade is low.
Even if the increased licensing costs isn't enough of a deterrent then there is the worry that the upgrade will require planning, testing and monitoring. The departmental application, running on SQL 2005, is familiar, it works, and the team knows from experience that upgrades are seldom stress-free. Will the application even run on newer SQL Server versions? What about the hassle of organizing development time to make the inevitable fixes, perform testing and so on, then retraining the whole team on using the "new" version of the application?
What about security? For the last 5 years of "extended support", users have continued to receive free security updates but beyond that had to pay for all non-security updates and support. Next year, support ends completely, meaning no more hotfixes or security updates and therefore potential exposure to security vulnerabilities. However, in many cases the applications that run on these old 2005 instances are not exposed to anything as adventurous as the Internet, and so are much less of a security concern.
Overall, I suspect the response will be rather more muted than Microsoft might hope. And, as one commenter observes, if you think moving people off SQL Server 2005 is hard, then SQL 2008 is "so capable that it's going to be almost impossible to eliminate"!