From what I can gather, Statesville Fire has had VIPER capability for some time. They may be integrating more radios into that system and leaving fewer on VHF.
As to VFD's going to 800, I know the south end has made the switch to Mooresville's system. I believe all their rigs still have VHF capability.
I am not sure what the departments in the middle of the county will do. Some of them have territory in fringe areas of VIPER coverage. Most of the north end cannot count on VIPER coverage at present.
There are only two VIPER sites in the whole county, Mooresville & Barium Springs. I would not expect an abandonment of VHF in Iredell anytime soon, nor would I expect Statesville to give up their VHF capability.
Other factors do play in this equation. ECOM dispatches everything in the county but Mooresville & Statesville Police Depts. I know ECOM has some type of 800 capability, as does EM for the county.