I have a iphone 4 and can't get ios 8?

Will all apps require ios 8 now because I have an iphone 4 Which can't run ios 8

There are no more software updates for the iphone 4. You need to have at least an iphone 4s to run iOS 8

All apps will eventually go to iOS 8 but most will do 7 and 8 for some time. WIth 4S and 5C free now on 2 year contract, there's no reason not to upgrade if you contract is up.

Welcome to the Apple world of obsolescence.
Remember Windows XP and the "end of support" after 12 years, but it will still keep working? This is end of working after 4 years.

Yes, maybe Apple wants you to buy a brand new one.