Depends on how exactly they are remastered.
I mean, I play on PC so if all they do is upgrade the graphics and patch out the bugs then I won't bother with it because I can get graphical mods and unofficial patches through Nexus. Now if they on the other hand were to remaster them and along with the polish to the graphics and ironing out the bugs and glitches they also clean up the game a bit and help flesh it out then yeah, I might consider buying it.
Like if they retconned the NPC who talked about Megaton's backstory which is completely absurd and said that the remastered version is now canon? Then yeah, that'd be pretty damn sweet. If they added more stuff to Megaton to help make sense of it, such as a garden, a hydroponic farm and giving the generic NPC's a couple of lines that indicate that they actually 'do' something rather than just loiter around then that'd be pretty damn good. If one of the bigger places which makes money in Megaton was owned by someone in Tenpenny Tower then that'd be even better. Yknow, flesh out the game and call it canon.
Now that I'd buy. But otherwise I can't see the point to it really. It's not like Fallout 3 and FNV ain't working on the PC, and I doubt they'd need to remaster either for Xbox One or PS4 when they can just port them. And I'd only buy it if it was reasonably priced considering that they 'are' selling the same game I already own 2 copies of, (3 for FNV).
Then again, I don't see why they couldn't just release this as a free content upgrade for PC users.