If you want to code for fun, try Codea.
If you get good at it and want to put something on the App Store, it can be done; though you'll still need the use of a Mac, Xcode, and a developer's account.
There are several apps in the store that were created with Codea, like Crabitron and Cargo Bot.
The problem with having Xcode on the iPad is that it's a powerful tool. Even if the newest iPads could handle the load, and they might, if rather slowly, you would still have to completely redesign the interface; because Xcode is also very complex. There is no Xcode lite for casual users.
While Swift is meant to be easier for developers than Objective C, the best parts of it, like Playground, actually require more computing power. another reason you're unlikely to see Xcode or Swift on the iPad.
As for me being happy, well, I'd love to see Apple's development tools on the iPad. I just know enough not to expect them any time soon.