Admittedly, IBM holds the ultimate responsibility for the demise of the AS/400 aka iSeries, aka System i aka Power Systems with the IBM i OS, but...
It has really been the customers of the AS/400 that have killed the machine. IBM is a business that responds to decreases in revenue by cutting costs and investing in technology that represents revenue growth potential for them.
The first big issue with the AS/400 (and all of its many names) was the fact that customers who originally bought software maintenance and hardware maintenance began to stop buying maintenance contracts. IBM made this possible by publishing all of its OS/400 and IBM i PTF's via their web site where any customer could download them free of charge. The very fact that the machine and operating system were as reliable as it was is another reason for its downfall. There are thousands of B model machines running around the world with OS/400 1.3 dating back to 1987 when the machine was first released. These machines are running vendor provided software from many vendors that no longer exist. These machines sit in a corner and just do their job.
While this a great testament to the machine and its architecture, it was not good for IBM. When IBM gives you a number of machines shipped, installed, or running they often include these machines. They get zero revenue from these machines.
The other and perhaps more important reason that the machine is dying are the programmers working for its customers. For the most part these RPG "programmers" are folks that were recruited from the file room, mail room, or folks that took a one semester class at a junior college and left their job as waitress, bartender, painter, or construction worker to become a "RPG Programmer". Most never bothered to take and introduction to data processing course or any other computer fundamentals. Many were taught by IBM SE's at the employers place of business.
These folks did their jobs most often by copying sample programs and modifying them to accomplish their businesses objectives. They were good employees and did their jobs but were hardly programmers.
IBM listened to many of its business partners (companies who sold commercial software) and more advanced customers with professionally trained developers and enhanced the RPG language and the language environment of OS/400 itself with ILE and many enhancements. RPG today is a very respectable programming language. With the exception of a lack of object oriented support RPG is as robust as any other language thanks to the folks at IBM and specifically the leadership of Barbara Morris.
A much touted benefit of OS/400 (aka IBM i) was the fact that programs written in 1969 for the System 3 still run without modification or even a recompile today on IBM's latest machines. This very positive feature eliminated the need for programmers to stay current with language and technology.
IBM also made the sad mistake of never dropping old features form the language. You can still use today's compilers and write code that looks like RPG II from 1969. There are millions of programs running on the IBM i that are basically RPG II. In fact most RPG programmers do not know how to write a modern ILE program or use modern features of the language. There are very few ILE service programs, procedures, etc.
Software vendors driven by cost control are still selling systems written in old architecture and programming style. Why change? Why modernize? Why above all spend money to rewrite an old system?
These are just two reasons that IBM i is destined for the bit bucket.
Read the original at Bob Cancilla on IBM i.