-As stated earlier, the PMBR has no intention to spend time and effort in coding a seemingly harder-to-make Wii U mod. Hell, they haven't even finished PM yet.
From studying gameplay, it seems SSB4's engine and API are likely to be based off of Brawl's. There's a lot of hints that the action/subaction system along with its unintentional flaws (platform cancelling as with that one Zelda clip) are returning. Brawl's API was incredibly simple, it just had a lot of commands, and the only hard part was documenting each of the commands. Melee's API set up for Brawl's, and Brawl's is looking to set up for SSB4's. That being said, the bigger chunk of PM's work goes into animation, which would, assuming a "BrawlBox" type program is made for SSB4 in the next couple of years, be of the same difficulty if not easier. And in addition to that, I'd say it's pretty likely that Sakurai didn't make a whole new API for the 3DS version seeing as how it was done so quickly, or a whole different one for the Wii U version while 3DS is using one comparable to Brawl. I don't think it would be too hard.
--With the stricter environment the Wii U has, it will probably be a lot harder to make a fully-functionable mod without facing issues from Nintendo (I'm not too sure in this one).
The Wii U is pretty much already hacked from the ground up; even deeper than the Wii was. We're talking stuff that would only be patchable by a new hardware revision. The problem is, unlike the Wii, this device isn't already in millions of peoples' hands. In the Wii scene, for every person interested in piracy, there were like 10 that just wanted to make their own Mario Galaxy stages, or Mario Kart textures, or hack Brawl, or just do things for fun. So far the small Wii U scene only is interested in leeching off of peoples' work and using it to make piracy-enabling apps.
The team that got all the way into the Wii U decided not to release their exploit until devs figure out how to get Linux working 100% in the sandboxed virtual Wii mode, to show that there's legitimate developers that are interested in more than just piracy... and it hasn't been progressing much. Here's to hoping MK8 and SSB can create a lively scene and we can get back to the good ol' Wii days.
-Even if a different group of people wishes to make a PM-like mod, I don't really expect it to happen anytime soon, and it will likely not be as popular as the one we have now, which, quite frankly, is a miracle by itself.
In the unlikely event that such a project takes swing, I will be too busy playing the original and vanilla Smash 4.
Keep in mind the timing, though. If another hack to the scale of PM happens, it'll be a loooong time from now. The Wii U exploit would have to be published, we'd need to go through the whole Homebrew Channel battle again and have someone make that stable/keep Nintendo from doing X/Y to prevent it, someone would have to make a Gecko OS/Riivolution equivalent, a File Patch code would have to be created along with some other codes, we'd need a rip of the ISO so we can start studying/editing, we'd need a PSA equivalent, we'd need TONS of documentation, we'd need all the file types analyzed, etc. We're talking years of work. PM didn't come out 6 years after Brawl just because the idea was thought up 6 years later, it's because, for the most part, none/little-to-none of it was possible until like 5 years later.
In 6 years, SSB4 won't be new anymore, we'll have a whole new scene and know like everything about it, and we'll all be hype for SSB5.
![Stick Out Tongue :p :p](/styles/default/xenforo/smilies/tongue.gif)