Can I upgrade my iPad 2 to iOS 9 after the release of iOS 10? With the imminent release of iOS 10, I'm wondering if I should upgrade my iPad 2 to iOS 9 now. Specifically, I'd like to know if I will still be able to do that after iOS 10 is released? (Currently at iOS 7)

I know that I'll be forced to upgrade one day, as some app I like won't support iOS 7 anymore, but I'm also aware that it will make my iPad even slower, so I'd like to hold off as long as possible. But, I don't want to end up in a situation where I can't upgrade to 9 anymore, e.g. because Apple stops signing for 9 after the release of 10?
iOS 10 is not available for the iPad 2.

Because of that, you will continue to be able to upgrade to iOS 9.3.5 at any time in the future. Apple continues to sign the last available firmware for all devices, which will be iOS 9.3.5 for the iPad 2.

Examples of how the last supported version of iOS for a device continues to be signed: here