I already think of dentistry as a medical "specialty" - obviously we are not physicians, but there's no one else who deals with teeth and the oral cavity. Some ER docs and ENTs extract teeth in unusual scenarios.
Dental Anesthesia by definition stands in direct opposition to the "Super GP" model that you describe. It was established trying to follow the medical model of separating the duties of surgeon and anesthesiologist in the name of patient safety.
There will always be a demand for specialists. I would say a majority of dentists do not have the ambition nor the desire to be a "Super GP" to comprehensively handle every single case and procedure they see. True "Super GPs" are the exception, not the rule. That would be exhausting, and you just can't be good at everything. Additionally, even if you can do that c-shaped mesial root molar endo or full bony horizontally impacted wisdom tooth extractions I think in many scenarios it's ethical to give the patient the option to have it done by you (the GP), or to be referred to a specialist. There are always procedures that dentists will want to refer out to get a 2nd or 3rd opinion on.
I loved endo and extractions and didn't really like the cosmetic part of dentistry, and there are plenty of classmates I graduated with who are the exact opposite.
I envision Implantology as a possible future ADA-recognized specialty even though there are 2-3 other existing specialties that claim implants are in their scope. I don't think dental sleep medicine will be able to say that it's got a large enough scope in the future to be able to define itself as such - same with cosmetic dentistry.
The American Academy of Dental Sleep Medicine was a little upset when the ADA recognized TMD and Orofacial pain as a specialty in March of 2020, since sleep medicine got lumped in with it. TMD/OFP programs typically also teach management of obstructive sleep apnea with oral appliance therapy. Don't know if there's enough breadth of knowledge in dental sleep medicine alone to justify being a full-fledged "specialty," although there are a few dentists who limit their practice to only that.
This is all to say that there's enough stuff going on in dentistry that you can tailor your dental practice to however you want to practice, and that's one of the major benefits of this career.