To be fair, the only thing that seems to be consistent between the two from a development standpoint is that the engine is developed by id. The rest is different.
I will hold on hope.
The world looks like it has the same empty feeling. I like Fallout and the Elder scrolls games because there's so much stuff you can find, but Rage had none of that at all. Everything that could be found in the game was bought from a few different shops. I'm kind of getting the feeling there won't be any kind of loot system in this one too.
If the combat is better, which seems to be the case, how long is that going to be enough if the game has the other mistakes of the first one?
I'd say that depends on the story. I haven't played the original Rage, but I have played Far Cry 3 and this looks a lot like that in gameplay style. It's a wasteland, by definition there shouldn't be a ton to be found--though should still be plenty to see.
If I took a guess, transitions between major battles are going to be via vehicle and feature some sort of combat objective, maybe races? I don't know if I'd expect a loot system, that's not the general theme with Quake and DOOM games and, while this is neither of those, I think Rage would probably follow a similar path--they're just not collection games beyond serving direct purposes.
I would expect that a lot of was learned from DOOM in terms of keeping that down time interesting. It's not the same developer, but they're still under the Zenimax umbrella.
I think I brought this up in IRC a while ago, but I'll say it again. The trailer for the first game looked great, but the game ended up being boring as shit. Literally every mission in it is exactly the same thing with no attempt at any variation.