The City system is not a Phase 2 type - so as long as the County decides to go with the same system type as the City is using, then you should be good to go with a little programming (and perhaps a few setting tweaks along the way).
It's simply not possible to speculate further without hard facts about what the County intends to do - but even if they decide to go X2 (I very much doubt this), the 800 works there, too. It's really a wait and see game to find out what will happen next
best regards..Mike