Older revisions of the board are no longer manufactured, so the latest revision is always what is currently for sale.
Although it's highly unlikely, nobody knows if newer board revisions will come in the future. Some feature upgrades may require them, but ultimately it's up to you if you want to buy it, or not. If there are newer board revisions in the future and you feel the need to upgrade you can always sell what you have to fund that upgrade. Plus there are places like Stone Age Gamer that offer a trade-in program for that purpose.