According to an update from BMG U.K.'s Charlie Stanford on Elvis Collectors Gold the follow-up to the "ELV1S 30 #1 Hits" CD will be released in September 2003. It will again be a compilation of Elvis' hit singles.
The update also mentions that BMG decided to do another remix like last year's JXL remix of "A Little Less Conversation". Appearantly they are still trying to find the right song for this mix.
Source: ECG / Updated: Mar 28, 2003