What the customer wants here is impossible, but some customers (larger enterprises in particular) will pay handsomely for you to try. Why is it impossible? Change is the one constant in our universe. Long after there is no consciousness left to perceive it, change will continue.
Red Hat are doing the same thing as Microsoft. You have a support programme, and then a more expensive extended support programme, and then sometimes yet a further even more expensive programme. Charging people for their over-confidence is a successful strategy, because every customer believes they are going to get off the old version in plenty of time, and many of them are wrong, but you don't care which ones.
If Enterprise desktop users want to pay $$$ for longer term support they could make it worth Red Hat's money to do this work, shovelling back the tide. But I'd guess that Linux has far fewer cases of "desktop" systems that are actually servers. I know at work there were at least two "desktop" machines sat in empty offices over the pandemic, switched on with big "DO NOT SWITCH OFF" notices because the Windows "desktop" software running on them was vital to normal operations, even though that's clearly very stupid and the software ought to live on a server somewhere.
Companies (and their budgets) like predictability.
Sure, it's unavoidable that you'll have to upgrade or abandon certain software, but it's an altogether different ballgame when you know exactly when that's coming.
If I know I've got guaranteed security fixes in whatever is installed on my system for 5 or 10 years, it means I only have to do the work once every 5 or 10 years.
That's service being provided, and I'd like to test that hypothesis sometime with starting a company to support your dependencies for a monthly fee.
Existence of enterprise Linuxes like RHEL and SUSE offering confirms the market is there, the biggest question is if the overlap of those willing to subscribe to such a model matches those who want this type of predictability. You'd be basically paying for distribution-type development focused on packages you need.
However, the uptake was so good that it was soon bundled in the regular Ubuntu support contracts, and I see it's available for free for a limited number of machines today (3 iirc, like Ubuntu Livepatch).
Maybe it is the driver for enterprises to get Ubuntu paid support today, but doesn't seem like it feom the outside.
Eg. Debian maintainers have taken a particular release of upstream software, and if upstream didn't provide bugfixes for older releases, maintainers in Debian would backport them and Debian users would enjoy exactly what they want: stable versions with security fixes.
Ubuntu LTS is exactly that as well, with a quicker release cadence (at least when it was introduced — was it 2006 with Hardy Heron? :).
However, business entities (like Canonical) are trying to move away from supporting users to such an extent because it's very costly (thus snaps and reduced "main").
Even though everyone using a dependency now has to pay the cost at unexpected times (which is ultimately more costly than distros doing it), market was obviously not willing to reward developers like Canonical sufficiently for it to keep at it.
RedHat is still doing it for their enterprise editions, but desktop users are being left out.