What do you mean obsolete ??
Have scientists found something faster than light?
Glass fibre, sheathed and run through ducting will not be touched for probably 50 years. Telstra has perfectly good fibre that was laid across the nullabor around 30 years ago. It is only when someone puts a backhoe through it that it fails.
All you need with fibre is an electronics box at each end. These are easily upgraded if you want terabit speed.
