I don't like the idea of Obsidian just making a new post-apocalyptic IP, the thing that makes Fallout (and Wasteland) great is it's rich lore and atmosphere, don't get me wrong Obsidian could almost certainly make another fantastic Apocalyptic IP with a deep story but it wouldn't be fallout and well, that's kind of the point.
But what is exactly is "Fallout"?
The original game? It's been - what? - 15 years since it came out? Lots of stuff changed since then. Even Fallout 2 has many differences to it.
Fallout 3 and Bethesda's take in general are such a radical departure from previous games that they're basically only Fallout in name.
Fallout NV, the Obsidian's attempt to mix older games with Bethesda's style is cool, but again, different from everything before.
And what about Fallout Tactics? That one is semi-canon, right?
Series' lore has been butchered and retconned billion times. It's gameplay differs with every new title. It's setting also has stark changes in tone and the locations generally differ greatly, from game to game. Even the vibe of the games is different from one title to another. Hell, even the internal logic of the setting is not continuous.
So in the end, what exactly is Fallout? Is there some thin red line common to all these games except for the fact that it is post-apoc, that it has retro-futuristic elements to it, and several recurring factions?
If it's all it has to offer, than this franchise isn't much of a continuous one.
tl;dr
Fallout as a general term is an illusion. The franchise has taken so many forms by now that there is hardly anything common to all these games, and therefore, the term "Fallout" has largely lost its meaning.
A new franchise with a deep story, original elements and (hopefully) more consistence in the future made by Obsidian would be a godsend.