It makes sense that things are kept vague but any vague mention should be the mention of good things. FO2 does not mention how there was a Vault Dweller that was the "scourge of the wasteland." They love him and build statues to him.
Going off topic a bit. Seeing as how FO4 most likely be on the East Coast do you think Beth will change the PA to Western Styles or stick with the ones they had in FO3? Or will they at least put in a Damage Threshold?
I think it really depends. In my viewpoint, T-45d Power Armor was the first model (at least I believe that's the lore. Correct me if I am wrong), and while T-51b is much better, since it came several years afterwards and close to the war, it was in short supply. Thus the east coast had a surplus of the weak T-45d in order to ensure that the President and other officials in D.C. and possibly the U.N. in New York (if it exists) were kept safe from riots and such. So in short I think they'll probably stick with T-45d just to keep their lore in check, but will probably have another T-51b, just won't have it as the primary model like it'll be in New Vegas.
As for Damage Threshold, I see New Vegas as a stepping stone for Bethesda. When they made Fallout 3 they left out a lot of stuff the fans would've loved to have in the game, and they'll see what's popular with New Vegas and what isn't. I can assume based on the popularity of weapon mods we'll have those in Fallout 4, but as for Damage Threshold it'll probably be again, based on the fans reactions. Do they prefer this over Damage Resistance, or do they prefer DR?