And this is the relatively easy case of an app built using Apple technologies. It can be much more difficult if you built a game using a cross platform game en

And this is the relatively easy case of an app built using Apple technologies. It can be much more difficult if you built a game using a cross platform game engine filled with binary 32bit libraries. If the engine is still around, you might be able to pay for a license for a newer version of the engine, but then you likely also need to deal with the SDK and format changes in the new engine as well as any iOS specific things you have. Still, if software is your business and this software in particular makes you money, it's really not _that_ expensive to do.