ewa090 and kenisned are right on the money...
First of all you would not need 40+ dispatchers to cover the county. I lived/worked in south Florida for a few years and the SO's are 10 times busier than most departments here. Palm Beach county for example has 5 dispatch channels (North, Central, South1 (Delray/Boynton), South2 (Boca) and West). Each dispatch channel has it's own Tac/Car-Car channel and then one dispatcher for "inquiry" (data requests when MDT not available/calls for tows and impounds, etc). The SO covered the entire unincorporated area of the county which is waaaaay more populated than Morris County and also provided dispatch for a few towns. Broward County, FL is another example and pretty much the same. I think if they can do it with 5-6 dispatchers, Morris County can. Of course, this doesn't include Fire/EMS dispatch and call-takers, but I think half the amount of 40 would be more than sufficient.
Second, there is no way all the towns here will give up there own dispatching. Look at the problems in Bergen with the UHF trunked system. Most agencies want they're own little domain that they can control. And agencies want things done their way, not the county way. For example, Orange County, NY wanted to dispatch all Fire and EMS in the county and take that away from local PDs. Several agencies said no because the county dispatchers don't know the area/people like the towns do. Additionally, you must be dispatched the county way and utilize their protocols. You can't have 40 different ways of doing things for each individual department. And later on when my EMS agency (who originally stayed with town PD dispatch) talked about switching over to county, we were told no because they couldn't handle our call volume, go figure.
Third, the current TRS in Morris County was not built for portable coverage. I believe it was spec'd to 95% mobile in the street coverage. That is ALOT different than 95% in-building coverage. I certaininly know what it's like to call on the radio and not get a response, have to walk outside and take my portable off my belt and hold it in the air and still get "your unreadable." I also know that many departments cannot afford $3000+ for an XTS5000 portable, especially volunteer Fire and EMS agencies. And we all should know that a Fireground should never be on a trunked channel (per NFPA)...so you would still need numerous analog simplex channels.
I think a big problem with PD's is the constant b/s chatter on dispatch channels. For example, instead of saying "10-98 report" when they clear a call, you'll hear "I spoke with the complainant, they were advised, information taken for a report, I'll be clear, blah blah blah." Also, car to car comms shouldn't take place on dispatch channels. By implementing things like 10 codes/signal codes/disposition codes, etc., MDT's for CAD/DMV, etc., radio traffic could be sgnificantly reduced thereby freeing up airwaves for more priority traffic.
Just my .02 which can't but anything anymore.