Valve has made it clear that no, you cannot will your Steam account or games to someone else when you die. The issue of digital game inheritability gained renewed attention this week as a ResetEra poster quoted a Steam support response asking about transferring Steam account ownership via a last will and testament. I never even considered merging Steam accounts, but at least granting access to the person named in your will or your legal heir seems like something a service like Steam should be legally obliged to do.

Source: After you die, your Steam games will be stuck in legal limbo – OSnews