I'd consider those products safe since Google is completely dependent on them internally.

Microsoft, Zoho, and AWS all have a mail/docs offering that one can count on to stick around.

Once I started doing just a little advanced stuff in Microsoft Word I realized how poor Google Doc is. You can't define your own style for crying out loud, you have to redefine an existing one.

Go is probably pretty safe, but even internally at Google Flutter is still sort of flying under the radar and nobody knows (or cares) about it too much. But if leadership decides to take a look at what the heck is going on in that corner of the organization... that would be a hard one to explain.

Go I'd consider, even if Google ditch it, the language still exists and is sufficiently entrenched to continue on. I wouldn't go near Flutter at all. Exactly the sort of thing that Google will lose interest in and stop backing leaving you with a product built on an un-supported platform.