I really only use my iPad 4 iOS 10.3.3 for SkyDemon. Increasingly and inevitably some other apps say they cannot be installed/updated because they need iOS 11, e.g. Google Earth.
I imagine SkyDemon support for iOS 10 will end at some point. Have you already made a decision when this will be? If not, I would be grateful if you could proactively inform in advance (say by email) when that might occur so I have opportunity to source a newer iPad.