CAN I UPDATE MY IPHONE 4 TO IOS 7 AFTER IOS 8 COMES OUT?

I'm still running ios 6 on my iphone 4 because I heard that ios7 slows down the iphone 4. If I decide later to upgrade to ios7, say in a couple years, will I be able to upgrade after ios8 is released?

You can because ios 8 is not available for iphone 4 i have ios 8 on iphone 5c

A couple of years they might not even have ios7 available anymore except by emailing support

Yes, you can. The final release of iOS 7 will be available after iOS 8 comes out because unfortunately iOS 8 is not able to run on the iPhone 4.

Also, with the iOS 7.1 update (which you can get today) dramasically improves the performance and speed of iOS 7 running on the iPhone 4.

Sure, iOS 7 on the iPhone 4 is a TAD slower than iOS 6, but iOS 7 MORE than makes up for this slight sluggishness with all of the great new features and enhancements.