Obviously, metas change from assassins to mages and back again, but every other lane has changed significantly. Bot and Top both got the alcoves. Top got Rift Herald a few years back, Bot got dragons. Jg is flipped upside down every preseason but nothing happens to midlane unless the champs themselves are changed. I guess the only major change is the addition of turret plating, but that happened everywhere and didn't fundamentally change Mid, it just made laning phase longer.