You won’t find many people left who still expect GNU/Linux to be a big hit on the desktop.

I don’t think that will happen anymore, and the desktop is no longer at the forefront of IT.
Linux on the desktop was seen as important because there was a perception that the desktop was the guide to where the IT market was going. The word desktop is a bit of a vague term, we used it as a form factor (“there is a desktop computer on the desk”) and as a programming metaphor (“there is code and files on the desktop”). It is now easy to use a desktop computer or a desktop operating system, whereas the word desktop is no longer applicable and was never relevant. It has been revived by laptops and embedded computers, which don’t actually have to be on your desk, but in practice often run a regular “desktop” operating system, especially laptops.

Mobile is currently the guiding device, the device that drives most new developments and where there is the most money for innovation (perhaps “AI” or “cloud” will take over, but that is not the case yet).
The success of Linux there depends on whether or not you see Android as Linux.

In fact, I don’t find the question of whether Linux will “break through” or “win” interesting. For me it is important:
a). That I can use the software I want, as an experienced and professional user, I have a fair number of desires and requirements. This is not sustainable if I am the only user, so I would like to see some success, but not necessarily “win” it.
b). Since there is diversity, I don’t want Linux to become the only operating system. To achieve evolutionary growth, you need diversity, which doesn’t work well with a single operating system. (In general, I think companies shouldn’t have more than 20% of the market share.)
c) To follow the philosophy of free software (Wikipedia: Free software) so that I am almost in charge of my computer and the algorithms that run my life, not a company or a government.

If you consider Android to be Linux, then Linux is clearly very successful with the general public.
But I don’t feel like it really serves the points I consider important. It could be worse, but it’s not great. Android itself is still somewhat customizable, see LineagOS for example, but Google has built so much on top of it that it’s simply locked down. The entire Playstore with all the apps in it and all the cloud services is still completely locked down. We don’t even have to talk about Apple.
Running Linux/LineageOS is not an end in itself, it is a prerequisite to achieving my goals, but in the meantime the scope has expanded. Where the goalposts used to be is now the midfield.