Like, you've all given pretty plausible reasons for the game to come out early, but we ain't no devs here, right? We're speculating and there's quite a damn chance that we're missing something big in the whole picture and that something is the exact reason why CDPR will use their time and involuntary quarantined summer to either polish the base game or, maybe, throw some more resources on something we'll see post-launch.
Hell, they may as well be concerned with the fact that the current situation has affected quite a few people's purchasing powers, which may put them dead against the early release as well.