Never dismiss the market potential for legacy applications. A genuine x86-compatible processor would be a godsend to a lot of industrial control devices. Could those tasks be done with ARM or microprocessors? Sure, if you had C code to recompile for the target architecture. It can also be done without RS-232 to RS-485 to Ethernet media converters and all manner of other kludgey devices. But it often isn't. ;)
For those of you who don't get it -- have you ever worked a job where you supported retail and industrial equipment? This isn't a dig or a set-up for a "then you don't know what you're talking about" punchline... You wouldn't believe what's still out there. Lots of ATM machines apparently still run OS/2! IBM just pulled the plug on sales not long ago.
In all seriousness, support for these systems follows the path of least resistance. An old application from 1994 that does the job will not get upgraded until that old 80486 with fur clogging all its fan inlets vaporizes in a final puff of smoke. Even then, the owners will beg you to locate a direct replacement. Maybe because there is no modern software, or it's an $80,000 license with much more restrictive usage terms, and will require a Windows 2008 R2 server with MS SQL Server to store its configuration files. Often just because no one has the slightest clue how to re-deploy a new version. They've memorized buttons to press, the company (or person) that originally installed it is no longer available, and the business would be lost if they were forced to shut down while they seek new options.
That said, I don't know that an Arduino-clone will be the device of choice for this segment -- especially lacking video and serial I/O out-of-the-box. There are other industrial boards that have this as standard equipment, and can still run DOS just fine. At 1GHz or better. (Not that speed is really much of a selling point here.)
OTOH, as the comments in the linked article said, this has the makings of a cool vintage gaming rig. I still have Mech Warrior and MW 2, King's Quest, Loom, Wing Commander, Castle of Dr. Brain, Willy Beamish, and a ton of other games that are getting harder to run on modern computers.