IBM still wishes we were in the mainframe age where a single vendor had supreme authority and maintenance fees rule the day. You can say that many of today's SaaS vendors have similar sway in their more niche markets but none have the almost complete dominance of their market as did / does in some places IBM.
I believe there are API-level emulation products for AS/400 and its descendants. Any company wishing to migrate off these machines (as off mainframes) can do so, as long as they manage the risks of porting and reimplementing the applications.
These lines are still popular because they offer something a rack of Dells can't - a nicely packaged solution of extremely reliable (and powerful, no pun intended in the case of i) hardware and software, exquisitely refined over many decades.
> I believe there are API-level emulation products for AS/400 and its descendants.
There are, and it isn’t a new thing - California Software Products came out with BABY/400 in the early 90s, to support porting RPG apps from AS/400 to DOS or OS/2-and Windows and NetWare versions were soon added as well.
But the problem all these solutions have - IBM i has so many gazillions of features, many of them legacy (sometimes with multiple different ways to do the same thing, just for historical reasons), none of these packages can implement it all, they can only implement a reasonably common subset. And if you are really lucky, your app only uses that subset, and it all just works. And if you are a bit less lucky, it only uses one or two extra bits that are easily replaced, and the rework required is modest. And if you are really unlucky - and the bigger your app and the more technical debt it has, the more likely it is - the bits missing may be so significant, using one of these solutions might not be viable.
One firm I worked at still has its old “mainframe” running all its cobol apps… but it’s all running on a windows server backed by a sql server database.
These servers are like enterprise iPads. We would be better off if solutions like it were vital. Instead we have the Microsoft ecosystem, and the scourge of malware and ransomware.
