747-Intercontinental Private plane is a bit of white albatross. 747 is an amazingly capable aircraft, but at the same time is exceptionally expensive to run estimated at 23k an hour. A single flight from Qatar to US and back would cost close to a million dollars. Reasonable when the cost is divided over hundreds of passengers but really adds up for an individual even a wealthy one.
There is limited aftermarket for 747i, large twins such as 777 are nearly as capable but have lower operation cost. There were way more 747–8 freighters sold so for an owner looking to offload a passenger or private version scrapping the plane for parts for freighters might be the best option like this one that got scrapped with only 40flight hours.
A large private plane even one with a gilded interior is far away from being usable Air Force One. Those planes need to offer all the communications, safety and command post operations as are found in the White House. The process of building new AF1 has already been going on for years with upgrades costing 10x the purchase price of the aircraft. Adding a third plane to modify would not get us any closer in time to having a replacement but simply add more cost and complexity.