Re: The way things are going with Office 36x (where x >>> 0)
I suspect that, if done well, Notes/Domino will have a decent niche in the future for companies that don't want to go cloud.
Microsoft is very committed to O365, and that means that future versions of Exchange will both lag behind in features, and perhaps even not get them at all. Some of those features will be obscure back-end ones - but when it comes to things like web access, it might be more obvious.
For example, if O365 gets a new web interface optimised for tablet displays, do you really want to bet that it's going to land in the next Exchange patch? More likely you'll have to wait six months to a year - and then there's the delays in actually applying that patch to your own infrastructure, such as testing and change control.
Notes/Domino might actually become a sensible choice for on-premises because of that. And even if it doesn't, hopefully it'll give Microsoft a reason to compete for on-premises business, rather than simply drive everyone to the cloud.