Like it or not, all iOS 6 apps will need to be upgraded for iOS 7

The reaction to the grand overhaul of iOS 7 has not been universally warm and fuzzy. Some are happy with it, while others are kind of freaked out by it. But, as the U.K.-based app developer group Entropy Labs astutely pointed out on its blog (via Daring Fireball), none of that matters: iOS 7 is here to stay, and if you don’t upgrade your current apps by the fall, you’re the one that’s going to lose out.

Everything about the look of iOS 7 has been tweaked or massively changed. Textures, colors, menus, buttons, navigation arrows, keyboards, dials, icons, everything will need to be updated to blend seamlessly with Apple’s(s aapl) new chosen design. Apple isn’t forcing this, but it’s in all developers’ best interest: because when you put an iOS 6-designed app next to an iOS 7-ready one, the difference will be incredibly stark — and not in a good way.

As Entropy says:

Remember what non-retina enabled Apps looked like when the iPhone 4 was released? Well, this has the potential to be worse – much worse. And remember when many people said that iPhone-only Apps would look “just fine” on the iPad when blown up to 2X scale. Yeah, that argument didn’t last long.

Simply put, pre-iOS 7 Apps running on the new OS stick out like a sore thumb – looking aged, clunky, and well…just ancient.

The deadline for this upgrade isn’t specific, but Apple says the official iOS 7 release will be sometime this fall.