I would argue she is not. her performances in alien and aliens are timeless, as well as her niche in ghostbusters. her steady work in the aughts and recent resurgence should be respected, avatar et al, however i dislike her cameo schtick at this point, and don't think her output of family films, comedies, and poor indie films matches her early output, which means her output is degrading and is not timeless.
if it's just looks... she is unavoidably getting old now and losing her special something, so not timeless to me