I'm not an insider, so take my insight with a grain of salt... but it's my understanding that the current runway of the GUM airport (Won Pat International) isn't long enough to handle the size of plane needed for long-distance flights b/w GUM and LAX. However, if you're on island, you'll notice that the Guam Airport Authority has already begun extending the runway. It's still at least a few years away from completion, but, once complete, it should be able to accommodate larger planes.
Here's a link about the runway expansion (an additional 2000'!):
http://www.guahanmagazine.com/node/696. The article states a completion date of April 2010, but I can vouch that it's way, way off. There's actually a road currently bisecting the runway extension, and it's not scheduled to be closed until 2012 at the earliest (and yes, you read that correctly: a public road bisects the runway extension... apparently runway protection zones weren't always incorporated in the past).
Kosrae, you mention that CO Mike services are in danger. What do you mean by that? I know that it's impossible to predict the outcome of this merger, but I'm personally most afraid of changes to our travel rewards flights (it's nice to only need 25k miles to other Pacific Islands/East Asia, and 60k to the States). I believe United currently requires 35k and 80k respectively. Yikes!
I assume you're in Kosrae and on the island hopper route? I'm very jealous... I hear it's an amazing place.