I did a focus group hangout with a Google staff member many months ago, and under the NDA I signed, and I can't discuss which product it was for. Most importantly, the staff member asked me what's stopping me from using their service over a competitor's service.
I replied, "I know they'll still be supporting/providing the service 1-2 years from now".
In general, nobody should be scared of such an eventuality. If large companies didn't have massive, major handicaps by their very nature, there would be no small companies.
I think in B2C markets, its definitely a fear. Witness how many people use Gmail because its free. But B2B products? I'd have no fear of Google coming into my market. I'd be more worried if it was Amazon, Apple, or Facebook to a lesser extent.
Be fair, I started using Gmail all those years ago because it was awesome. And although it's stagnated and they're about to fuck up the desktop UI by "Materializing" it, it's still pretty good.
I replied, "I know they'll still be supporting/providing the service 1-2 years from now".