GMail supports SMTP an IMAP access, so they won't lack GMail. Youtube supports web access which frankly is better than the Google App because it doesn't nag you all the time. Google Maps up until recently was just another navigation app which are a dime a dozen. (For a while there it wasn't a particularly good navigation app, but they've really pick up their game recently.) I have no doubt can build replacements for them all.

But all those apps in the app store - that's a problem. Google's lead in speech recognition - that's a problem. Google pay - that's a problem, particularly as the app store is tied into it. Google's lead in image processing and cameras - that's a problem. Google's amazing ability to translate languages - that's a problem.