While it may still be some time before IPv6 support is an absolute necessity, it now makes sense when buying devices that may have quite a long life to look for those that include IPv6 support. I already have an LS-XHL which I expect to be using for several more years; if I was buying today I'd be trying to buy a NAS with IPv6 support.
So let's get IPv6 support added.
QNAP and Synology both appear to support IPv6...