I am only aware of a single modern-ish motherboard with ISA, the MS-98A9, and it only supports Intel 3rd Gen Core series CPUs.
That said, if it was a large enough project, reverse engineering and re-implementing using modern components would likely be feasible. Turning each of these into network services handled by something more akin to a RaspberryPi could modernize the data sources while providing a sustainable and modular replacement strategy. The problem is that its not "sexy" enough to get a major government project, and it would not grease the correct palms that a multi-billion dollar next-gen complex proprietary replacement would.