Maybe my concept of procedural linking terrain is different from Gizmo's, or everyone is just misunderstanding what he's talking about; but what I have in mind when I think of using procedurally-generated terrain is to increase the size of the world map and lower the density of pre-set special locations........
That is it... and one way to do it that springs to mind are defined zones of wasteland, where you leave a hand made set-piece (like a town), and enter an expanse of auto-generated wasteland (that looks the same as what you see in FO3), eventually coming across areas like wasted industrial parks and derelict bombed out suburbs, apartment blocks, strip malls, later coming to a major shopping mall (this could be a set-piece, hand done with quest NPC's and inhabitants ~or not, and could be an auto-generated interior "dungeon" with forgotten loot of several kinds, or just something special hidden inside ~or not). Trek some more (towards your intended destination), leaving the mall, and off into more wasteland, more junk yards, more crater valleys, more apartments, houses, drive-ins, ghost towns, warehouses, dirt roads, subways, Always with the threat of encounters both animal, humanoid, and environmental as Radiation zones could pepper the land with potentially lethal exposure in some places. Have a map that's 100 square miles instead of 16, and always of course, the option to fast travel to locations you've been briefed about ("Here let me put this on your map..."), or places you've researched or downloaded information about.
Have an encounter in Fast travel, and the game pulls you out of it into the auto generated wastes, where (if you survive the fight) you can continue the trek in real time, or fast travel again to get where you want.
*Another point is that the game need not really retain all the information about the wastes indefinitely, because you'll not likely come that way again ~ever; This works to advantage as Special encounters cannot be returned to.