We will be living in the remodeled old house or the finished barndo full time for the next 3 years. Then we will be moving away (but plan on leaving behind much of our stuff: tractor, lawn equipment, boats, hunting and fishing gear, tools, guns, etc) and will come back to use the property intermittently for hunting and fishing. Might settle down there full time or at least a few months out of the year a couple decades from now.
The main idea behind the barndo is that we could have it be a nice new build (no old house issues) and it would seal up better than the old house for when we aren't there.
We would strive to rent out the older house as is and try to find a long term caretaker that wants to live on a pretty nice hunting and fishing property at a cheap rent price in exchange for some basic upkeep. Basically we would be very selective and try to find a long term, extremely trustworthy renter that can dual hat as a caretaker.
The barndo would be more than we really want to spend right now (probably 100-120k) and might be a challenge to finance (would need to finance about half), but we could offset the higher initial price with the rent from the old house and having a test run with a renter while we live up the hill a ways would be very nice.
The property lays out pretty well so both house locations would have decent privacy.
Our other option (and what we are leaning towards) is to go ahead and put about 30-50k into remodeling the old house now and if we want to build a barndo or another house a decade down the road then do so. The main issue there is storage of our stuff once we move away in three years. That could be a problem if we choose to rent out the old house once we leave the area.