Its probably not that much work, considering the resources IBM has, and if there really are customers actually wanting this type of thing.
I'm sure there are some out there somewhere.... Much like you can bet there are some mainframe people not ready to give up their SNA networks either...
An OS/2 personality for text only apps on NT was developed by MS/IBM using the native NT API and included in the initial NT releases. And IBM later developed a full OS/2 personality (including DOS emulation) to run above the IBM Workplace OS (i.e. a Mach variant) - this was released as the aforementioned PowerPC port. Creating an OS/2 personality above the more functional POSIX API would arguably be easier than either of these two previous microkernel style APIs they have targeted.
Lots of people forget that Windows NT started out as NT OS/2. And they kept the 1.x personality, but threw away the "cruiser" 32bit personality and took that WILO port of Windows 3.0 to OS/2 as a starting point of porting Windows to OS/2... It's in some old book "showstopper".
I guess the question is, would you implement it on top of LIBC, or tie it to the kernel with syscalls to make it more 'native' to the kernel?
Without having the source to either, who knows... I'm just glad it's not my job.
Running OS/2 apps on "proper" OS/2 in an x86 virtual machine still leaves you at the mercy of a 10 year old OS. Compared with OS/2 apps running natively as processes, it is more resource intensive, and it hinders you from taking full advantage of modern hardware features such as threads etc (it all depends on how the virtual machine is designed though). Also, apps are only as reliable as the underlying OS, and nowadays, some might be more comfortable with that being Linux on raw hardware, rather than the OS/2 kernel running on emulated hardware above another real kernel on real hardware.
Which is true, as long as you never programmed around that quirky OS... Just look at all the fun the Wine people have had, to the point they have to be bug for bug compatible.
Sometimes I'm surprised nobody has tried.. not everyone wants to run Unix, but ReactOS is still coming along in Alpha stages, but it's too fragile for day to day usage...
I guess the real thing is that unless you are XYZ corp with this internal app (which will never see the light of day for external testing) what great OS/2 programs are there to test with? Sure I've got Excel 3.0 for OS/2, but it's the 16bit stuff.... And OS/2 1.3 runs great in Virtual PC!