I dunno... maybe it's just me, but I can't exactly see how to translate some of Fortnite's core aspects into Smash - not easily at least. With Minecraft, Steve (or the player) can build stuff, but you can also make armor, potions, weapons and paraphernalia. So there are multiple ways to implement crafting into Steve's moveset.
The way Fortnite works would mean that, to be "as accurate as possible" Jonesy would need to be able to build stuff that modifies terrain, like walls or stairs - most of which, if I'm not mistaken, don't exactly break in one hit in game.
Not that it's impossible, because at this point I don't think any playstyle truly is impossible to implement, but I have to say that at least to me it sounds like a balancing nightmare. Unless they take a lot of creative liberties with it, like, say, stairs that work as an up special and then disappear when the animation is over.
On popularity terms, though... it's not something people can deny - though I still think there are other mass appeal games that would have priority over Fortnite.