Want to bet Motorola is behind it all? Think about it. Migrate off the T band to "standard UHF" band, which would require MOST agencies to purchase NEW equipment. And government agencies have a bad habit of paying FULL price AND overages.
No doubt the manufacturers are spending billions of dollars on "strategic business development" (not only that one, but ALL of them), but this one was (in my view, anyway) on wireless companies lobbying Congress. So, in the places where this spectrum is needed the most - everywhere but NYC (and even there, only one agency was saying they don't need it) - what is there? There isn't enough non-T-band UHF to do a 1:1 replacement of all the systems in the NYC area, nor in the Los Angeles area (LA is also heavily dependent on T-Band).
Much of the newer stuff runs contiguous 450-512. There are usually two UHF splits - 406-470 or 450-512. I'm not up on Harris subscriber products, but Motorola radios from HT1000 and up, and Astro Spectras and up ran these bandsplits. The base station stuff was more frequency dependent. But the available spectrum isn't there.
As for paying full price, most agencies buying off a "state bid" list or some other cooperative procurement discount usually got 20-30% off. Where they got you was how things were put together and with COTS device and firmware upgrades. PC-dependent stuff was only as good as its manufacturer supported it. So, if you had something that was chugging along on a 286 computer (or a VME computer with a GPIB interface for external devices), and those aren't supported anymore, you'd have to replace it with an upgrade (ka-ching) even if it worked fine, because if any part of it broke, it couldn't be serviced anymore. The system would be dead in the water while someone cruised eBay. There are also situations where business partners back out or deadline a product your system needed - i.e., Cisco has a VoIP thing your stuff had a TAPI written for, they pull out for whatever reason, and you substitute it with Avaya - except its costs are different and it works a little differently - and the TAPI has to be recoded and tested, and if it's prematurely implemented becomes buggy and unstable (BTDT - and it's painful).
Back to competitive procurement - RR's forums are loaded with examples of how these blanket procurement agreements seem to thwart competitive bidding from local vendors. Even standards-based systems that use single-manufacturer proprietary adulterations to the standard (like $8 encryption that's only available in that one manufacturer's equipment) do that.