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I wouldn't worry too much about the end of mainstream support, but once it reaches the end of extended support, it really is time to move on. As a practical matter, there really isn't much difference between mainstream and extended support. Once extended support ends though, security updates end, and that is when you have to upgrade.
The conflicting information is due to there being two different support deadlines, as PCWorld explains:
Microsoft will stop mainstream support on January 12, 2015. But the company will keep providing extended support until January 14, 2020.
Basically this means you'll get complete support through the first date above. After that and until the latter date, you'll get free security updates and not much else -- unless you want to pay for a subscription.