Besides maybe fixing Fallout 2's inconsistent NPC sprite quality (you can see that the artist left BI mid-development after finishing the tribal sprites and some others, and the rest of the new ones look like ass) and the inventory UI, I don't see what they wouldn't be able to fuck up. The gritty but still aesthetically pleasing environments and NPCs are not something a digital art sweatshop in Asia could replicate, we would probably get too shiny/clean renders instead.
In a perfect world someone could competently remake Fallout 1 into a superior game (better tactical combat, overhauled perks, better party NPC system, some more content and expansion of locations), but such things are better left in the realm of dreams in [current year] with modern game designers running about, especially since some moron would no doubt get the idea to make it first person. BTW heretical thought of the day: immersive sim Fallout 1 remake might not be an entirely bad idea, but that's even less realistic than someone properly remaking the game since it would require even more brains to pull it off properly. We would get Bethesturd's dungeon crawler with guns take on Fallout instead.
Anyway if anything should get the cashgrab remasturd treatment then InXile should instead be remastering Arcanum instead of the Fallouts. Those fugly sprites would benefit from being replaced with 3D models (also I want the Chapeau of Magnetic Inversion to show up on the PC's head for the

factor), and they should remake/overhaul the combat system and AI while they are at it. Environmental art is also very hit or miss in Arcanum. Although I guess they can't do Arcanum even if they wanted to until the M$ assimilation of Acti-Blizz is complete.