Recurring costs are budget killers. A radio network offers the ability to aggregate costs into the system, but costing out each subscriber unit is a big deal. Yes, it might be "cheaper" than paying for 300 FTEs, but that scenario is the exception, not the norm. Go to "fly-over territory" where agencies are making conscious decisions to buy heating oil to heat the fire house so the tanks don't freeze or diesel fuel so that they can roll apparatus. Then, factor in 50 volunteers who now must pay (either out of pocket, or through some other arrangement) the recurring cost to connect the subscriber equipment.
Moreover, there are many unanswered questions that the dream weavers have not answered. Like how would an agency know that there is an impairment or outage in their area of operation? When they go on a call and the thing bonks out for them? When the subscriber unit indicates "NO SERVICE?" And, then what? The grand plan is to migrate to infrastructure-dependent technology in the next 15 years and abandon LMR and auction the frequencies. Whether that comes to fruition or not is immaterial. The same minds that think there is some kind of tactical advantage to someone who is OUT OF POSITION being in the loop on command and control (as if the incident in Memphis is going to be run by some incident commander in Atlanta... that might work in the fedworld, but in public safety, it's called either "irrelevant" or "ridiculous") think that this system is actually useful for more than a data network.
In my conversations with proponents, resiliency comes in network diversity. That's nice. There are loops or mesh to heal a dig-up somewhere. What of the last mile? Do they get diversity? The indication is that the proponents intend to usurp 4.9 GHz for connectivity. It's being carved up as I type, not that I think a lot of those paper licenses are real. But it will suck to be in an affected area and have to wait 72 hrs for someone to truck out a COW and generator. And, if that resource is committed to a particular part of a widespread affected area - and it's not yours - it's going to suck to be in that area that will stay dark. With 100% migration to the platform, and all carriers down (or experiencing a GPS outage), expect a lot more action on FRS and MURS blister-packed radios. From public safety users.
In my opinion, the people who dreamed this thing up either do not have any public safety experience at all, or were given a rubber gun decades ago (or are stockholders in prospective system operators).