I think you underestimate the potential popularity of BF3.
In particular because it is one of the big shooty franchises (the other being CoD of course). We know shooties are popular, they are the most popular game type these days. As such it'll be popular just for that alone. People want to play the new big name shooty.
You are also correct about people being excited for it on the PC in particular. EA has gone to lengths to make it a good PC game, giving PC gamers things they want like DX11 support, larger player counts, dedicated servers and so on. That too will increase interest.
Even if the game ends up being total crap, it'll probalby have a good bit of sales from preorders and BF/shooty fanboys. If it is a good game, and it seems like it will be from the tests/previews, it is likely to sell real, real well.