The AAAA record is not the only new DNS record IPv6 has brought us.
RFC 2874 describes the A6 record, a proposal intended to replace the older
AAAA record, described in RFC 1886. The major difference is that A6 records support
record chaining, to make network renumberings easier.
So there is a (slight) possibility that the AAAA record might become obsoleted
some day. Considering how slowly the IPv6 protocol itself has gained
popularity, though, it'll take ages.