The developers of the AHNVEE project share your sentiments. Those very same sentiments, as well as the experience that you allude to "for potential tourists looking for more than the all inclusive experience", are all a part of what influenced their decision to locate here in Sos?a.
Although the business model is "all-inclusive", their demographic is not what would be considered the typical "all-inclusive" guest. The "typical AI" guest in the Dominican Republic is here more for the budgeted travel package and inclusion of "all you can eat and drink" inexpensively, with emphasis on never leaving the resort property.
As I mentioned earlier, the AHNVEE demographic is ACTIVE adults, seeking a Caribbean vacation including adventure, fine dining and relaxation. Their guests are ENCOURAGED to leave the resort property and experience the unique adventures offered nearby. Even though they are providing exclusive private areas with resort services included on both Sos?a and Cabarete beaches, guests will be enjoying the opportunity to explore the diversity the two towns and nearby areas have to offer, outside the walls of the property.
As far as Sos?a maintaining it's uniqueness, I don't think that will ever be an issue. I'm not sure how long you have been visiting here, but from personal experience (I have been living here for 15 years and visiting for 25) I don't see Sos?a changing enough to lose the qualities that make it attractive. And since many of the positive qualities are associated with its geographical location and setting, e.g., proximity to airport and public transportation, calm safe bay and harbor, numerous beaches, nearby mountains and rivers, etc., it will always remain appealing.