I don't think administrative work needs any killer applications. You need a complete system which actually works together and can be sourced by a single vendor.
You're assuming that people want to switch but I'm talking about the incentives for end consumers to switch. There has to be some strong motivation for switching, and it's not only going to be GUI design. Something about a new OS must be really desirable, either the hardware it's running on or better applications.
I'm using Linux as my daily workhorse since 2008 so I'm not opposed to it in any way. But the fact is that due to lack of integration with the OS, every Linux application is slightly less good than its commercial MacOS and Windows counterpart. GIMP is slightly awkward to use in comparison to Photoshop, LibreOffice can replace Word but definitely isn't better, pro audio applications are virtually non-existent for Linux and work only as good if you don't need any pro plugins (very few of which are produced for Linux), Dia, Inkscape, and other vector drawing programs are far less good than e.g. Affinity Publisher, and so on and so forth. Linux doesn't even have good content indexing comparable to Spotlight. Applications don't even have consistent user interfaces.
Administrative work needs 2 killer suites to work: Microsoft Office and the Adobe design suite.
Any replacement for these will basically have to be a bug for bug clone if you want them to work. LibreOffice is 80% of the way there, but it still mucks up too often to be reliable. PDF viewers are plenty, but there's no effective replacement for Acrobat, InDesign, Illustrator and Photoshop[0].
Third party vendors you have to work with for other things (ie. Printing folders) require stuff to be in the formats made by these two software suites and their response to "your printing press isn't following the PDF spec" isn't gonna be "oh sorry, we'll migrate our hardware", it's gonna be "the printer says no and my other customers don't complain so just send me the files correctly."
Since Adobe and Microsoft are the default, this is something third party vendors can say and get away with. The shoe is on your foot, not on theirs.
[0]: GIMP doesn't even come close to being a Photoshop replacement, they do very different things. Photoshop is a photo editor + drawing program, while GIMP is aimed at image manipulation. The difference comes into play with how the interface is designed and the complexity of certain actions in each program. GIMP is designed to let you do specific individual things to an image, while Photoshop is more aimed at giving the user entire workflows.