Re: Another 20 (18) years...
Apart from scripting and interpreted languages...
But "all" software is compiled, regardless of platform. Your argument doesn't make sense
And the problem will be the same as the DVLA system, old systems that are no longer supported, where people don't have the source code, don't understand the source code or the system is so delicate that nobody dares touch the code!
A previous employer wrote Linux based software, but it was proprietary. Up until 2015 they used a version of SUSE Linux Enterprise Server from 2000! In 2015 they couldn't get any more RAID controllers that would work with the SLES drivers, so they were forced to move on, but even so the software was only partially updated and it was still using Qt libraries from the late 90s, because they were too cheap to pay for upgrades.
Some of the calculations were so complex even the programmers who had been with the company since the beginning were reluctant to change anything!
Heck, they only turned off their DEC Alpha in 2014, because their last customer had migrated to a SLES server with software from 2000!
Having access to the source doesn't mean that you have the people or the skills to solve the problem, and having solved the problem, you still have to test everything in combination, to ensure that it doesn't suddenly cause other problems elsewhere.
If the devices are stuck on an old Kernel and can't be updated, having access to the source isn't going to help, for example. Likewise, if it is a locked down device with no access to the system, even if you can fix the problem, you still need the original supplier to install it for you, if they are even still around.
The same problem exists with Windows in industry as well. A lot of old industrial hardware has Windows based controllers running Windows 9x or XP, because there is no newer software that will run on a newer version of Windows.