Let's clarify, because you need to seperate land rights from inheritance rights. The fact that he happens to be executor in no way affects existing land rights he may have as either an easement beneficiary or easement grantor.
First: does the decedent's land benefit from an easement across executor's land or is the executor the beneficiary of an easement across the decedent's land?
Second: if land now owned by the estate is subdivided, it is still subject to any prior existing land matters such as easements, right of ways, setbacks, etc., in addition to any state, county and local municipal land division ordinances having to do with access, conservancy, minimum setback requirements, minimum lot sizes, waste disposal requirements (such as if there is a requirement, for example, that each proposed lot pass a perk test for a mound system, and so on. It is not a given that land CAN be divided into the number of lots desired by X number of heirs. They will inherit shares of the undivided land and go from there. If a party (such as the executor) also owns other contiquious land, that would not necessarily have any bearing on what they are entitled to inherit from this estate.
The easement, as stated RUNS WITH THE LAND, and not affected by the health of the easement grantor/beneficiary. He is entitled to the easement, and any future subdividing needs to be based upon not encumbering that easement.