I won’t comment on market share, but even if theoretically QGIS totally displaced ArcGIS Pro/ArcMap/ArcGIS on the desktop, the arena of competition has shifted to ArcGIS Online and its competitors. And once you’re in ArcGIS Online, Pro becomes the convenient choice for desktop editing.
LibreOffice could be miles better than Office on desktop, but the competition is lost because Office on desktop is just an accessory for Office 365 (which competes with Google Docs/Drive).
Disclosure: I work at Esri.
It would be nice to have better support for browser-based sharing and editing, but the desktop-based parts are there already.
The comparison still works in some ways though, because ArcGIS is selling you both the software (ArcGIS Pro, Map Viewer, Field Maps, etc) and the backing services (hosted feature services, basemaps, locators, etc), similar to how Office is selling you data hosting, sharing, and mobile + web app integration.
You can accomplish the same things with QGIS, GeoServer, QField, etc, but then you’re in the position of building a GIS from parts. Whereas with ArcGIS, setting up a new map and database (feature service) for data collection is a point-click workflow.
Of course you pay a premium for that level of integration.
Theres other complexity too, like 'how to avoid silent failures in ArcGIS Pro and Hosting Server'.
Case in point: say you use amazon RDS. URL for that object is name.customerID.environment.amazonrds.com . Its a long URL. Now you go into hostingServer/ArcGIS/manager and go set this as a data source. You can validate the data source and everything's fine...
Until your analysts add projects in RDS and go past some secret legacy arbitrary length of DNS+path. And if you do? Things will silently break, data won't come into ArcGIS Pro right. Anomalous errors.
Now, if you change the RDS DNS name to an IP address, all those problems go away! Everything's fixed, analysts are happy, and none are the wiser.
Until, Amazon does maintenance on your RDS, changing your IP address. Then, your environment then breaks for no good reason, and you have to be keenly aware to go to server manager and MANUALLY rerun data store check.
And no, ArcGIS monitor can't do this.
And... Dont even start me on 80070035. That "premium" support ticket was rotting for 5 weeks, until I ran into an engineer on LinkedIN, who solved it in 30 seconds.
A lot of shops I know (private and public) will use ArcGIS still, but I'm noticing an increasing number of people (particularly younger researchers/analysts) who are exclusively using QGIS.
QGIS is powerful and full featured, but it is admittedly a bit rusty around the edges, especially when working with very large datasets. If they keep working on fixing some of the sharpest edges I think it will go on to have a good future. Just in the past few years I've noticed significant improvement.
In many ways it feels like Blender -- long ignored and dismissed, but slowly but surely improved over time, and then suddenly became quite a big deal.
For me the real ongoing question is the role of MapBox, MapLibre, to some extent Google Maps API, and other web-first solutions. It's difficult for Esri to connect with the average web developer or researcher who just wants to start with clickable pins on a map.
Maybe for home or casual use, sure. I use a ~$4500/y Esri license level and it's worth every penny.
Also, plenty of people are still using matlab!