My parents have an iPad 2. It's still in good condition, battery still very good. But they can't use it anymore for Skype: Skype delivered always slower apps as

My parents have an iPad 2. It's still in good condition, battery still very good. But they can't use it anymore for Skype: Skype delivered always slower apps as the time went on, and now the last version of the app is too slow to be used at all: when somebody calls the app gets so big lag that it just fails. Also, some app writers make the app compatible with every iOS. Not Microsoft. Even newer versions of Skype aren't for iOS 9. But the last for iOS 9 was already too slow. From this perspective, the biggest problem are the companies which decide not to test on the older hardware and which don't want to support older iOS versions.