All of these articles seem to be saying "X Player will transfer" or "X Player leaves Y school".... but that's not really what the portal is. Entering the portal means that a player is looking to transfer.... not that they will or that they've yet left a school. The portal allows them to gauge interest of other schools, and it puts their current school in the position of having to make a decision - do they continue to recruit this player, or cut him loose and look elsewhere?
There will be something like 1200 players in the portal this year - and I can't imagine 100% of them will end up at another school or without a scholarship; some non-zero percentage of them will end up continuing on with their current school.
I know a lot of fans are of the mind that entering the transfer portal makes a player dead to them, or that they'd be unwilling to take the player back - but I can't imagine coaches are thinking that way, and if one of their key players is in the portal they'll almost certain be talking seriously with them about whether there's a door open with the player to possibly return.
Johnson and Young are completely different situations.
Johnson has a much much higher focus on academic value than almost any other player - and he's exploring what might be the best fit for him to have a school pay for his graduate studies while he plays basketball. Since he hasn't been able to talk to any programs (namely Stanford, UCLA, and USC), he doesn't know what their expectations are.... it's likely that one or more of them will make every effort to accommodate his academic needs, but there's the chance that no where feels like it'd be a better opportunity than Rutgers. While I feel that there's a 99%+ likelihood that he's gone, there is still a chance he returns (imo).
Young, though, is bound for a professional team next year, but he's looking to see if anything else out there might be more attractive. I see 0% chance that he returns to Rutgers, and a pretty low chance he ends up at another school somewhere - I doubt he's being eyed up by Gonzaga or Baylor or anyone who might have preseason expectations of a Final Four, and he'll likely be paid to play somewhere next year instead.