Small businesses aren't nearly as attached, and the Office experience sucks on mobile and web. There's definitely a market for someone who can get that right, and I don't think that someone is Microsoft. I say this as someone who is irrevocably attached to Excel (and to a lesser extent, Word and PowerPoint), I don't think Microsoft is currently willing to cut off the entire ecosystem of software based around Office on the desktop, but if you were to make a clean break, make it cheap and have it work great on web and mobile, a new player could have a shot. There's tons of people going to Google and their suite isn't great, what if it was?