I personally would not live in Sullivan County. As you mentioned, there is a large Orthodox Jewish community there, and unfortunately, they tend not to maintain the areas in which they live. See several communities in Bergen, as you mention, and also the problems in Lakewood NJ, Kiryas Joel, and Monsey / Kaser in Rockland County. I live a few miles from one now, and its not safe, its very run down, and many areas are unsanitary (dumpsters overflowing, decaying food around, diapers on dirt patch front lawns, old mattresses and furniture left outside, etc).
Keep in mind that all of the land used as religious properties are tax exempt. In Sullivan County, that's a lot of land. That leaves the schools, police, fire, bills to be paid for by everyone else. Even though they use these services as much as anyone else. Using, but not paying. Nearly any house or dwelling can be considered a "yeshiva" and therefore, tax exempt.
Also, a huge $6 billion development is slated for Mamakating (the town that surrounds Wurtsboro) called China City. That's billion with a b. Basically, it will be a huge complex with housing, hotels, malls, casinos, and amusement parks.
"On the surface it all sounds fascinating, but in actuality the real intent of the project could be for a place for emigrants from China to live.":
From Borscht to Egg Rolls - Sullivan County Post
I wonder if it will be approved, but considering that it would be somewhat unique to the US and that part of NY is struggling big time, it could feasibly happen. Something I'd definitely want to make sure I was aware of, as it will change the semi-rural character of that area significantly.