Two thoughts on your post:
First: I think we have to stop and remind ourselves why we like "good and cheap." The answer is because the more "good and cheap" pieces we have, the more resources that are available to purchase additional talent. THis means we eventually have to USE those resources for the math to work out. These cheap pieces are critical for the foundation of a successful team, but if we fail to shift our sights at some point, then we fail to capitalize on the advantage that it afforded us in the first place. We could have very efficient production all around the field, but if those guys are all 1-3 win players, we still aren't going to win any games.
Second: I think all of the scenarios you mentioned are realistic and possible, but I don't think any of them are MORE likely than the standard scenario: useful-but-mediocre players remain so, and Machado remains a star level player.
Further, even if you do get a logjam, I don't think you've really got much of a problem at all. Because again, "good and cheap" players are valuable trade chips. It's also worth considering how much more valuable depth is in the current game than it used to be. For example, if it turns out that Anderson is a 4 win player, Machado is a 5 win player, and Sanchez is a 3 win player, you still may get a TON more value out of using Sanchez as a utility guy who can rest either player without a substantial loss in production, and who can step in a starter should either hit the disabled list.
My point is, I don't think you ever really have to worry about having too many good players, because desired assets tend to be fungible. The only thing you have to worry about is if too many of those players end up BAD. In that scenario, with so many holes to plug, can you afford to put so many resources into filling just one?
Now, if Anderson becomes a star in the next four months and Machado INSISTS on playing SS only, that changes the calculus. But we'll know about that before we get a chance to sign him.