Hi glanceblamm,
The biggest wear factor today is the pressure level of the cartridge. Today's barrel steels mitigate that somewhat but as pressure increases, barrel life decreases. When the swedes were made, both formulation of steel alloys and their heat treating were delicate arts. 129gr @ 2600 or even 2700fps is still modern ballistics, just not magnum class. The pressure limit for the 6.5x55 ensures a very long life.
Ultimately the issue later will be, can one still get a turned replacement barrel for the rifle at a reasonable price. When the last of the supply is gone an original condition rifle will be valuable again as they really will be history.
Paul