It appears as though there's
a lot more buildings that are open and part of the larger world than there were in FO3/NV, and nearly all of the released footage of the game corroborates this, what with much of the action taking place outdoors with open buildings visible all around. Todd Howard also made the claim that there's a lot more open buildings, which,
yeah yeah, but again, footage corroborates this.
So far we've only seen two areas which seem like they required loading screens (though no loading screens have been explicitly shown, just fades to black) -
the Super Duper Mart in the leaked Gamescom footage (please note the large bank next to it, with the wide open door), and the
building that Preston Garvey is holed up in in the Xbox E3 press conference footage (please note the several open buildings on either side of the street leading to Garvey's building). Large buildings being seperated by loading screens is understandable,
considering the number of unique physics objects and NPCs each might house, and that Bethesda might have felt that some interior designs would benefit from not being constrained by the outside size and appearance of those buildings.
Nearly everything else we've seen has been open - there's houses, businesses, gas stations, large settlements, and even
skyscrapers that aren't separated by their own interior loading cells and are in fact part of the greater world. And it's been confirmed that things like settlements, cities, and large outdoor areas aren't separated by loading screens (the hazy area with the Deathclaw from the initial footage reel might be its own cell but I forget where I heard that from), which marks a definite improvement over Fallout 3's heavily segmented DC and Fallout New Vegas's sectioned off strip/Freeside/Westside/Vault 3 Fiend Encampment/etc.
So, in other words, I expect large, intricate interiors to be the only examples of load screens this game will offer up, and I'm okay with that, given how load screens are much more commonly seen than in just that type of environment in the last two Fallouts, and how technical and creative constraints somewhat justify it.
Todd's word is god, since he's the game designer. There are loading screens for buildings, same as Skyrim, Fallout 3, Fallout New Vegas, Oblivion.
And for those of you who read this and instantly think, 'oh man, things haven't gotten any better have they', keep in mind that we've been given looks at just two large interiors that might require loading screens from the overworld, and many more places that don't seem to, alongside confirmation that load screens for large and important world areas have been nixed entirely. Here's an assortment of examples I pulled from the two and a half minute combat trailer (which, for anyone who hasn't seen anything beyond the initial E3 streams, or for those of you in the inexplicable "hardly looks better than Fallout 3" camp, really deserves a rewatch
since a higher quality version is now available. To the latter crowd, make sure to put in your goddamn contact lenses this time, lmao, because if you ain't seeing meaningful differences, you're literally legally blind.)