Several Eldar models, including phoenix lords, warlocks, and at least one of the farseer models, range from rogue trader to 2nd edition in age. Oh and the Avatar. Also vyper jetbikes. So somewhere around 1990-1993. I think there's about 20 eldar models that are around 20-28 years old. I think the dark eldar beastmaster and beasts are the same age.
Not saying your basilisk shouldn't get an update too. But I'm not sure a new basilisk will actually look much different, as it's already a plastic kit that looks like the platform that it's designed to replicate. More likely is that they'll remove the basilisk entirely, and try and copyright the imperial guard lineup by making the vehicles more distinct from the real-world counterparts. But this will be a big investment for GW and I doubt they'll bother.