I’m just going to say one last thing before I call it a night. what do you guys think caused Isaac to be removed as an assist trophy in smash 4 and why is it that we feel different about his chances now after that has happened? My friend who is a Isaac supporter like me wanted to hear from you on that.
I think we've covered it in this thread before with many of our theories, though it's hard to say for sure in the end. I think a general consensus is being due to hardware limitations that the two versions of the game imposed. Specifically the 3DS one, where they cut out a lot of stuff and even Ice Climbers because Sakurai even said they couldn't get to work with things like 8-player smash.
The problems that Isaac runs into with this is similar to a lot of the wall items and ATs like Helirin that create extra surfaces that probably interfered with many of the scrolling stages because there were some strange physics going on between the two versions.
It's quite possible that Sakurai planned to bring on a Golden Sun character but decided against it due to Dark Dawn's failure, seeing as Sm4sh was largely a relevancy inspired cast save for few. In which case, I think you could still potentially run into a problem if Sakurai decided to incorporate the Move psynergy into a moveset. I don't think we'll ever hear about it, honestly and it's possible that it's simply wishful thinking. Something I will point out and agree with that other users have stated. Creating a perfect Isaac moveset would both be easy to do and hard to do. Easy with the theory-crafting level of drawing up the skeleton of a moveset that he can do. There's just too much source material to draw from. I think it is actually harder to stay faithful to what most of us have in mind for what we're proposing Isaac to do and would take a little extra work.
If you had him going with Djinn, or using large psynergy attacks or some other gimmick they would require more playtesting and balancing than a normal character than say, Marth. And Sakurai is a stickler for the details, so you know that if he is going to make Isaac it'll be in for a penny, in for a pound. I'm sure that if we do get an Isaac we'll be satisfied in some way with it but it probably won't be what we're expecting.