A present-day startup would have to be insane to spend cash on installed office software, when GApps and other cloud-based offerings offer features for free that cost $$$ and take serious configuration effort to get working with MS Office, such as collaboration/sharing (Sharepoint! Ugh!)
And once a company is using a browser-based office suite, I can't see them migrating to MS Office as they grow, except for some specialised tasks, such as large-scale financial modelling in Excel.
Word is massive overkill for intra-company documents, and I honestly prefer http://prezi.com to Powerpoint for presentations (though Keynote is still top of the heap IMHO).
I'd be interested in seeing a web-based equivalent of MS Access - super easy database creation and hosting. Anyone got any links?
It all spells trouble for MS in the medium term, I would say.