A better question would be: what software technologies will not be around 20 years from now? My bet: Babel, npm, Vue.js, React, Angular, Zend, most of the SaaS/IaaS we know and use, Kubernetes, Visual Studio Code, ...
So, things that are old but still around are more likely to still be around: Unix, SQL, emacs / vim, fan-favorites lisp and forth ...
Web / CSS frameworks / mobile frameworks are less likely to be around.
Relational databases will be around forever. The nature of data does not change. Relational data will always be a good fit for an RDBMS.
I think skill in low level languages like C will have less market share in the job market, but always needed. It could be a lucky financial boon for people who have these skills, as they will be a rare commodity.
Almost everything presented as something new in the software development field actually just retreads something from the past. Truly new ideas and techniques come along rarely.
e.g
Java / C#/ C++ / JavaScript / Python
Oracle / SQL Server
Unix / Linux / Windows
SAP / ERP Systems / Mainframes / Cobol
Apart from this, We will see lot of changes the way we do development. We will see lot of improvement in automation / No Code / RPA etc
Now for the losers:
Web browsers will be gone. Windows will be gone. JavaScript will be either a painful legacy language or have been transformed into something entirely different. JS frameworks will be an anachronism that old programmers chuckle over while drinking beers.
I'm betting on
- unix-like systems
- SQL-like systems
- vim
- "core" aspects of programming languages (data types, algorithms, operator precedence, etc.)
- HTTP protocol
- program design
- security
Niche stuff:
- Lisp, in some form or another will continue to exist.
- Forth will continue to exist because it is possible for a single person to revive it.
Common stuff:
- vi/vim will live on. I will stop typing if it doesn't.
- JavaScript is probably here to stay.
- Java seems like a safe bet for longevity.
- Spreadsheets. Maybe not Excel, but spreadsheets will live on.
As for new technologies I would expect them to appear and take the niches where current technologies are not good enough. Take C++ vs Rust for example: the former is quite bad in terms of security and the latter is good at that. So Rust will become more popular in writing security critical applications and web services. But C++ seems to be good enough for things like high performance/scientific computing so it will be still widely used there.
Which is a shame as many would have migrated to Python 3 if it was turing complete
It will start making it's way deep into hardware