It is not the last halo. Its the last halo that Bungie partnered with Microsoft will make. Bungie is now partnering up with 343 Industries and will be creating more halo games. I've heard rumors of re-making Halo:CE and Halo 2, but I doubt it since they aren't really that old. Although it would be pretty cool.
@OP: I personally think Halo Reach is broken. They took all the skill out of the BR/DMR and turned it into luck. Its not good for the competitive gamer, like myself. It does have some parts that are fun and interesting tho. I still play it, but I still prefer Halo 3 over Reach.