An Easter egg hidden deep within Wake Island — which ships as part of the the game's Back To Karkand expansion pack — shows the number 2143 scrawled on a wall.
Alone it means nothing, but fansite BF3Blog points out that DICE has a habit of revealing future sequels in existing games. Way back in 2006 it included hints about the then unannounced Battlefield 2142 in Battlefield 2: Euro Forces.
If meaningful, the number 2143 could potentially indicate a follow-up to the sci-fi spin-off, which we'd definitely love to see running in DICE's new uber-slick Frostbite 2.0 engine. Of course, this could be nothing more than a lowly artist having a laugh.