In the same way I don't trust Google not to cancel whatever it is they just announced, I don't trust apple to keep supporting software on platforms that aren't theirs. They just don't have a good track record and no real incentives. The last widespread Apple sosftware on non-Apple platforms was probably iTunes, which was terrible.
Apple's recent track record (Apple Music, Apple TV) is surprisingly good. The apps on Windows and Xbox have been trending better/gaining features at a good pace with respect to Mac OS and iOS.
There is a sense that Swift has opened up cross-platform app initiatives at Apple that they wouldn't have done just a few years back.
I do trust Google not to cancel one of their core (or most popular) products, like search, Maps, Docs, Android, etc. Anything else I don't. I do use Google Photos, but I wouldn't be too surprised to see them shut it down one day.
