No, they most likely won't. XP has been on (free) extended support for FAR too long. Extending support for MSE on XP is still easier. They will still provide support (security updates) for corporate and government customers on a subscription basis IIRC. Getting any updates past XP's EOL won't be free anymore.
They probably considered Win7 hadn't penetrated deep enough in the market. Moreover, they also had several successful joint operations on bringing botnet command centers down in the last few years. Since most trojans on XP rely on these command centers to get their 'thing' going on to zombify infected XP machines, making further security updates, at least for home users, will be moot. Sure there may be another security issues crop up on XP past EOL date, but the most prevalent 'disease' in XP was zombified XP botnets. There's no reason to provide further updates (for free) on a shrinking market. Even AMD has started to distance themselves on XP support on their newer hardwares. Compare that to, say, Adobe products. A suite is way more expensive than WinXP, and see how long the free updates last before they require you to upgrade, with a fee, for further updates; three years at the most. Hell, even until now MS still provides free updates for Office 2007 via Windows Update (well, 'Microsoft Update' if you're still on XP; Windows Update only provides OS updates). People who'd still b!tch about MS ending support for XP needs a kick on the 'nads.
Yep, this isn't for security holes in the OS so the title is very misleading: Basically, the day XP stops getting security patches is the day all hell breaks loose and everyone who has been holding onto XP only exploits are going to release them into the wild. What use is a virus definition when you have a gaping hole anything and everything can come in through? edit It'd be like running Win98 with an antivirus and having a false sense of protection. Or getting a flu shot and thinking you are now protected against all illness.
