  We project the reach of future lepton colliders for measuring CKM elements
from direct observations of $W$ decays. We focus our attention to $|V_{cs}|$
and $|V_{cb}|$ determinations, using FCC-ee as case study. We employ
state-of-the-art jet flavor taggers to obtain the projected sensitivity, and
scan over tagger performances to show their effect. We conclude that future
lepton collider can sizeably improve the sensitivity on $|V_{cs}|$ and
$|V_{cb}|$, albeit the achievable reach will strongly depend on the level of
systematic uncertainties on tagger parameters.
