According to John Cross (you'll have to read through some Higuain stuff to get to it, though), newly-promoted Crystal Palace are looking for some help at the striker position, and they're looking to Arsenal to get it. Manager Ian Holloway (remember him?) is "keen" to bring the Costa Rican in on a season-long loan, which would hopefully allow the player to gain Premier League experience and take the next step in his development.
Since coming to Arsenal a couple of years ago, Campbell hasn't kicked a ball in anger in Britain. He's failed to secure work permits each of the two seasons he's been an Arsenal player, instead spending a season at Lorient in France and one at Real Betis in Spain.
Campbell has 24 caps for his home country, though, and has featured in their World Cup qualifying campaign. Costa Rica are second in their group, two points behind the United States and level with Mexico, though both Costa Rica and the US have a game in hand on the Mexicans. The point: Campbell plays regularly for a team that's about to qualify for the World Cup final. He should be able to get a work permit.
If he does get a permit, this would be great for club and player. Getting Premier League experience is a critical part of growth, and at 20 years old Campbell is right at that age where he can play at this level, but not yet for a club like Arsenal. If not, honestly it would be a bit of a blow. One way or the other Campbell is likely to be loaned out this year. If so, Crystal Palace would be a fine landing spot.