No, the official DICE servers for Battlefield 3 aren't mysteriously disappearing. Don't get a hernia or something.
There have been rumors floating around the those official online servers were going away, leaving only the privately rented servers available. But according to what EA told GameSpot , this really isn't the case.
"DICE is not shutting down servers. If DICE-managed servers appear unavailable, it is because they have been rented and customized by players. DICE will continue to add servers and will reserve a percentage of servers for players who prefer to connect through DICE-hosted servers."
If you weren't aware, DICE lets you rent BF3 servers for the PlayStation 3 and Xbox 360 at the cost of $25/month. If you do this, you can create exactly the multiplayer experience you want, which means you can decide on the maps and game modes, and also gives you the power to kick out the instigators (or anyone you want, really). Obviously, there are plenty of people who take advantage of this, because DICE needs to add more servers. Hopefully, this will happen soon.
So it's not that they've disappeared, necessarily; they've just been rented. Some don't really like this idea, by the way, as some who host servers can act…well, downright childish at times.
Related Game(s): Battlefield 3