De acordo com a Valve, o processo de fechar a autenticação via Won estará concluído no final do corrente mês:

“This process will be completed on July 31st. This means players will no longer be able to access Internet features of Valve games, such as Counter-Strike 1.5, using the WON authentication servers. Users can continue using Valve games on the Steam service by downloading the Steam installer and setting up a Steam account. For more information visit Counter-Strike 1.5 players will be upgraded to Counter-Strike 1.6 free of charge through Steam.”

Fonte: SteamPowered

Parece que os finalmente a 1.5 tem os dias contados.