Fallout 4 is not as big as you think
Apparently Fallout 4, the most anticipated RPG of 2015, is going to be quite small in terms of the space it'll take on your hard-drive. Listings for the game on the Xbox store show that it's clocking in around 28 GB.
This might be cause for worry, but then again it may not. We already know that Fallout 4 isn't looking for the visuals that other RPGs like Witcher 3 went for (despite the controversies, it still is a beautiful game). So that could be one factor. Even then, Fallout 4 still looks good enough to belong in the current generation.
Additionally, according to this tweet made earlier this month by Bethesda, Fallout 4 has more lines of dialog than Fallout 3 and Skyrim, so we know that content hasn't taken any hits.
And let's not forget that the game is getting a season pass for DLC, as well as regular updates once it's released, so I wouldn't go freeing up just 30 GB of space for it on my console.
But at the end of the day I don't think I'll be needing to expand my hard drive for at least a couple more months, and that's more than okay with my wallet.