The other thing is, if you are reticent about going to Windows 10, then you are probably reticent about going to newer versions of Office as well.
Mix that in with no more hardware support from Intel for Windows 7 on the last couple of generations of chips, it will be increasingly hard to get new hardware that will run Windows 7.
Also, as some point there has to be a cut-off or new operating system features can't be taken advantage of. Ms get criticized because their own software doesn't take advantage of new OS features, then, when they finally start to make moves to take advantage of new OS features, they are criticized for abandoning older platforms... They are damned if the do and damned if they don't.