At the end of the day this port means nothing for anyone but steve.
A port would absolutely not be enough to persuade sakurai for MC or BK to be included/not included.
Maybe minecraft wii u could have been part of a deal but it wouldnt be the reason for Steve joining either.
TBH I really don't think it means much for Steve.
"Chances" are an arbitrary concept for Smash speculation. There is no real scale for which characters are likely and not likely at this point. Every character inclusion is a deliberate choice, and they are there because Sakurai wanted them in the game, and because the copyright holder was willing to co-operate.
The fact of the matter is, none of us work for these game companies (and if you do then
shame on you for obeying NDAs :V), so we really don't know for certain what they are and aren't willing to do. A bunch of you for some reason thought Square and Nintendo weren't on good terms, and if they were, Sony would somehow intervene in terms of letting Cloud into Smash.
But look where we are now.
Same holds true for first party characters. I'm still going to wave around the fact that the speculation community didn't take Rosalina seriously as an addition for their own silly reasons, and instead only considered characters like Bowser Jr and Waluigi for Mario - yet, Rosalina was
THE FIRST new character mentioned in the initial presentation Sakurai made for the game and was the first new character revealed post E3 2013 (meaning she was finished enough to show off), and Bowser Jr, while in the game now, was actually almost cut because of time constraints. :V
Granted he comes up with all of the new characters before he develops any, but it goes to show where his priorities really lied. Basically the opposite of the speculation community in this case.