No.
It means employees still working won't build up future service benefits in the scheme. They'll still get a final salary pension for past service (though the "final salary" will probably mean the salary when the scheme is closed rather than salary at retirement - upgraded in line with inflation subject to various caps for various different periods - mostly 5% IIRC).
Basically existing members will be treated as if they left employment at the point when the scheme is closed and have the same entitlement to a deferred pension.