Hey there! Just thought I would create a post about what we have already seen in Fallout Shelter that may and hopefully will appear in Fallout 4, feel free to add any hints you think you've seen aswell but what I've seen are:
-As we all 99.99% sure there will be a series of vaults on the map they will probably have such recreational rooms as we can see in FS. This is actually a really goodmimprovement (if it happens) since exploring vaults in F03 and FONV became tedious after a while because of how alike they were. I'm guesing these vaults (some of them) will have rooms such as gyms and bars! (Also wasn't it Vault 122 in FO3 that had the tranquility lane quest... just thinking that, the vault 122 in FO3 sounds awefully like vault 111 in FO44.
-In FS we have different levels of the same weapon such as lever action rifle and armor piercing lever action rifle. I'm thinking what if you have such variants in FO4 which provide you with the relative additional attributes. Also maybe there will be enhanced weapons or most probably the ability to craft enhanced variants of the same weapon, kind of like the unique weapon collection in FONV.
-Obviously, FO4 is going to have a baseball/football theme in it! And in FS we can get a sports fan outfit which resembles a football player, I'm guessing we will get the opportunity to wear something similar on FO4.
-The Fat Man! Has anybody notied that your Dwellers won't use the fat man indoors? Maybe it's just me but they won't ever use it inside the vault! I'm thinking the fat man will be a tad more powerful in FO4 than in the previous Fallouts. Perhaps it produces a much larger nuclear blast? One which you would have to be crazy to make inside any room in the Wasteland.
-Unique Weapons. I think from seeing other vawiants of weapons such as the Wazer Wifle we will see a weturn of weapons that have higher attributes than their twins but welatively the same.
So far, this is all I have thought of but I shall update this post as and when. Thanks