Will old, pre-explored worlds never have strongholds? [duplicate]

All chunks generated before 1.8 will use the old world generation algorithm. They will never contain strongholds unless they are deleted and regenerated. Also, chunks from 1.8.x have a much lower stronghold-spawning rate, so even if 1.9+ generation will spawn a stronghold there, the 1.8 chunks will be devoid of them. However, newly generated chunks will contain strongholds, so all is not lost.

If you wish to find them, I'd recommend going to a 1.8+ chunk (there will be a visible line where the generation changed) and use an Eye of Ender.

EDIT: It seems that 1.0.0 has not in fact implemented the increased spawning that was promised. Silly Mojang! However, the rest of the post still holds.

Anecdotal answer: We have a stronghold discovered in a world that was started in Alpha. It was in previously unexplored territory. We had to go to a part of the world explored in 1.8 & use the eye of Ender to find it.

(Thankfully the end portal was intact.)