As much as we would all like that, I think it's doubtful. If anyone has a chance of getting to try the game early, it'll probably be the mods, not us lowly forum-dwellers. I believe a couple mods have been invited out to hang at the studio in the past (Sigi and Sard, I think?), though not to test the game (more of a general meet and greet, as I understood it).
While I agree with those who have said a public beta need not be exclusive to multiplayer games, I can see why it isn't. It's all about perception. With multiplayer games, it's OK if players don't have the best first impression (it shouldn't be, IMO, but it is nowadays) - it's a "collaborative" development effort, and few such games are actually finished on launch. They're happy to let players in to break their games early because they know the game is going to be constantly iterated on, with new features, characters, maps, etc. added over time.
In Cyberpunk 2077, we are getting a contained singleplayer experience, with the possibility of DLC later. If you open it up to the public, what happens when players finish the entire game, or a sizable chunk of it? Maybe you just lost a sale. I'm gonna go out on a limb and say those of us who spend hundreds upon hundreds of hours in these games are in the minority. I'm sure a lot of people play the game once, just do the main story and a couple side quests, and call it good.
If you restrict them to a very small portion of the map, the testing isn't of much value (not no value, just perhaps not worth the potential PR nightmares and expense).
Not going anywhere in particular with this post. Just presenting a bunch of different viewpoints, I suppose.