Not necessarily. Easements are often for a person, not the parcel, so if they are not mentioned in the new deed they might cease to exist. Parcels become landlocked in this manner.
You're right Mamazelle, adverse possesion almost NEVER happens. An example would be if a property owner had abandoned the property for many years and someone had created a dirt road for ingress. Then I could see a court possibly giving rights that the taker had he had not had previously had.
Mamzelle make a good point fishtank. If you're worried about what your buyer may do to you after the sale, I don't think you have much to worry about. Your situation would be coomparable to someone who had property near a school and the students often cut across the property. I don't believe this would be something that would even have to be disclosed.
Mattafact, if you bring it up and make it an issue you may be creating a problem that you don't need this close to closing.
I'm not giving advice, but if it were me I'd probably just put up with their crap for the next 3 weeks and let the sale go through. I don't think "the seller didn't tell me that the neighbors were a$$holes" would be grounds for litigation.
Disclosure: I haven't sold RE as a fiduciary in quite a while and I'm not an attorney!
You're correct. I would look to the deed, as that would take priority as to who has what rights.
As far as your second point, I don't think any property owner can truly be "landlocked". From what I understand if you own property you always have to have access.
What kind of access is the gray area. You may not be allowed to build a concrete driveway, but I'm nearly certain that you must have ingress and egress to any property. It's just a matter of how "ingress and ergess" is determined.