I would be amazed if elemental comes close to achieving the sales level of a civilization game, or having the same awareness or recognition levels at the moment as the civilization series.
It might be a similar type of game, it might gain a better critical reception(+be a better game), but only the most ardent fan would expect it to sell as much as a civilization game/be as popular as one. Not to say it hasn't got a chance, but the odds are certainly against it.
If I remember correctly, Sins of a Solar Empire was one of the 10 best selling PC titles of 2008.
If you think of the PC games coming out this year total, all of them, are you saying you couldn't imagine Elemental being one of the 10 best selling PC games of the year?
I'm trying to think of all the big PC games coming out in 2010. Starcraft 2, Bioshock 2, Civilization 5, C&C 4, um... So yea, I would say that Elemental is right up there.