Yeah, customers spending money is indeed an incentive.
In any case, effectively no new machines restricted to 32bit are sold anymore, so 32bit linux distributions will die out sometime soon. Bad luck.
Just to be clear, a 32-bit LabVIEW will run on a 64-bit distro. I think there is a lot of confusion about this because most software that comes with a 64-bit distro is 64-bit, and sometimes they don't come with the 32-bit support libraries installed by default, but those libraries to exist, and you can run 32-bit software (including LabVIEW) on those distros. The primary advantage of 64-bit LabVIEW is that it can access more memory, not that it can run on a 64-bit system. Most of our Windows users still use 32-bit LabVIEW even when they are running 64-bit Windows, and all Macs these days are 64-bit already with no 64-bit LabVIEW. You don't need 64-bit LabVIEW just because you have a 64-bit OS.
The most compelling case for NI would be a "significant" number of users telling them I will buy so many 100 LabVIEW for Linux licenses if a 64 Bit version is available.
What about not loosing even more customers ?
32bit machines (except for the embedded world, which isn't even supported by NI anyways) are hard to get - not produced anymore for many years now.
Eventhough the LabVIEW source code is written with multiplatform in mind,
No idea about LV, but NIKAL is NOT multiplatform. It's fundamentally based on x86/32 + PCI specialties. (otherwise nobody would ever had ridiculous ideas like userland heap for DMA)
it's a large source code base which takes quite a lot resources to make sure it will work on a new platform.
I've been running and developing for 64bit machines (of various architectures) for about 20 years. I really wonder what NI takes so long. Slept for 20 years, still sleeping.
Another problem would be the fact that even a 64 bit LabVIEW version would be of limited value to many users, without an according 64 bit DAQmx, NI-488.2 and NI-VISA driver,
Write proper IIO/Comedi drivers, publish them for mainline, and you're done.
Costs: about 4..6 man-weeks per device type.