MS Office is IMHO also slowly going to "die". The future is in cloud platforms, I already use Google Docs most of the time and except for some very complicated graphs which I have to do for my job, it would be able to everything I need. And there are alternatives. Not to mention all the other advantages such as having the data backed up all the time, access from anywhere... yes there are of course disadvantages and some documents will be better to create offline and as I mentioned, there are situations where it isnt enough yet and you need the advanced feature MS Excel offers, however, the majority of people use Word for just some simple typing and Excel for some simple tables, so for them it will be enough. And in the future I am sure the browser alternatives will be able to do just as much as the offline counterpart.
And if they also work on the security, having it encrypted, using VPNs etc. then even companies might migrate to it. Office also has its online version, but I dont think it is as good.
However, that said I still dont think MS is doomed. Remember that even today, majority of their profit is not from Windows, which is also why they now offer it as a free upgrade. We must not forget about their server solutions. MS Azure etc. Most people probably dont even know about this, but so many companies use this and the profit this generates is much bigger. As their competitor I see especially Oracle, VMWare etc. Companies pay billions to MS for support, maintenance, licenses etc. The home licenses for Windows are really nothing.