Well, it may be becoming a legacy, but I don't think it will ever actually go away. Even if only because of stuff like DHCP, TFTP, and multicast (and many times NFS, although where I work this is being phased out in favor of NFS v4, which I believe is no longer UDP, for it's security features).
Edit: I stand corrected. NFS v4 (at least according to the RFC) should still work over UDP.