What can you do in Slackware that is impossible in Ubuntu?
In Slackware, you learn how to do things on any Linux distro. In Ubuntu, you only learn how to do things in Ubuntu, Debian, and Debian derivatives. I owe to Slackware the fact that I can sit down and work with any Linux distro out there. It doesn't include its own special tools for anything, so you are forced to do everything the "standard Linux way," which is the way that works on every distro (with some special exceptions, like DSL).
This option worked for me.
Instead, the method back in that I've found for those of us who started in the "old days" is to go for embedded systems development. The embedded world uses 10+ year old technologies, so your experience with assembly language programming and writing software for systems with limited amounts of RAM and storage space is a big plus for embedded systems development. There are plenty of companies still creating software for processors that run at between 4 and 20 MHz with anywhere from 256 bytes of RAM on up to a handful of kilobytes of RAM. I've found this sort of development work is much more interesting, anyway, and people with old school knowledge are considered more valuable, rather than a dinosaur, for such work.
As it is, programmers aren't given enough time to write software that works bug-free. Schedules are always rushed. This would dramatically increase: the burden on developers, the quantity of bugs, the number of developers being fired because they didn't get a project accomplished nearly as quickly as someone who pulled off a similar project 5 years earlier, the frustration of the users and developers (and transitively, the number of heart attacks around the world due to elevated blood pressure), the number of security vulnerabilities in software, and the migration rate to processor vendors who didn't make this mistake.
In short: this guy is on crack!