not to mention a whole pikin stage already in the game

Not to mention a whole Metal Gear stage in there.

Thanks for the feedback!
I personally only put Roy's chances over Ike's because I feel that he has more of a fanbase. ROY'S OUR BOY, and what not. Though I personally like Ike more, moves wise.
Same reasoning pretty much goes for Lucas without someone to compare him too.
I do agree with the time argument. Just look at... well Shiver-Star already said it perfectly.

Also, with that reasoning, I do now feel like Zero has a REALLY good chance.

I speculate Wolf and/or Falco.

I'd prefer Wolf, but Falco would work for me.

Falco is a shoe-in if Multi-Man appears in the game

I was thinking, and if the devs would have announced Chibi-Robo now, there probably would have been a better reaction to his inclusion.

Lets play a game to spice speculation up a little bit by speculating one character in each of these catagories:
Shoe-In
Likely
Surprise
Not Likely
No Chance
Hell No
Wishful Thinking

Example...........................Or you could do this
Shoe-In:..........................Shoe-In:
Falco................................Luffy

Likely:..............................Likely:
King Dedede......................Luffy

Surprise:...........................Surprise:
Ayumi Tachibana................Luffy

Not Likely:........................Not Likely:
Shadow............................Luffy

No Chance:.......................No Chance:
Pichu................................Luffy

Hell No:............................Hell No:
Birdo................................Luffy

Wishful Thinking:...............Wishful Thinking:
Hawlucha..........................Luffy

I am calling it right now! I speculate Lucas and Simon Belmont for SSF2!!

OK then, this seems fun. Let's give this a shot:

Shoe-In: Pit
Likely: Roy or Ike (whoever would have a more unique moveset)
Surprise: Taizo Hori (aka Dig Dug) or Klonoa
Not Likely: Waluigi
No Chance: Wii Fit Trainer
Hell No: Shrek
Wishful Thinking: Young Link (with an original Majora's Mask based moveset)

Shoe-in:
Falco

Likely:
Pit

Surprise:
Ryu Hayabusa

Not likely:
Zoroark

No chance:
Amy Rose

Hells nah:
Mr. Incredible

Wishful thinking:
Greninja

Shoe-in:
King Dedede

Likely:
Pit

Surprise:
Marina Liteyears

Not likely:
Waluigi

No chance:
Lanky Kong

Hells nah:
Princess Daisy

Wishful thinking:
Jill & Drill Dozer

Shoe-In:
PAC-MAN

Likely:
Simon Belmont

Surprise:
Zoroark

Not Likely:
Daisy

No Chance:
Scrooge McDuck

Hell No:
Ridley (Sorry Guys)

Wishful Thinking:
Shovel Knight

Shoe-in:
Bayonetta

Likely:
Mewtwo

Surprise:
Ayumi Tachibana

Not likely:
Ike

No chance:
Shadow

Hells nah:
Snake

Wishful thinking:
Daisy

Shoe-In:
Ganondorf

Likely:
Falco

Surprise:
Ice Climbers (I'd be surprised if they were even able to implement them)

Not likely:
Bandana Dee

No chance:
Roy

Heck no thank you:
Riku

Wishful thinking:
Blaziken

Shoo-in:
Ganondorf
(He's a major character in the Smash series, not to mention one of the most controversial.)

Likely:
Ice Climbers
(A ton of people miss them since they were cut. Along with the devs' more advanced knowledge of Flash programming since the roster change [it was programming difficulty that was stated as the reason the ICs and Olimar weren't on the original roster plan], it looks to me like they have a decent shot now.)

Surprise:
Luffy
(Despite all the potshots we love to take at the guy due to being yet another anime character, he obviously has plenty of fans, and does make sense alongside the existing ones, having crossed over with them plenty of times before; if there was going to be an unlockable character in the Shōnen universe, he'd be it.)

Not Likely:
Duck Hunt
(Considering that poor Mr. Peepers was utterly reviled at the time of the roster change, not getting a real fanbase until 2014... yeah...)

No Chance:
Ryu
(Despite his recent surprise inciusion in Smash 4, he's still basically the poster child of our rival game, Crusade. I don't think his inclusion would be that well received here [although it would be welcome from me].)

Hell No:
Dark Pit
(As "controversial" (meaning absolutely hated) as he is, he would probably be the easiest last-minute clone to add to pad out the roster if there were going to be any at all; being a recolor and not a remodel, he'd be more practical for a sprite format than Dr. Mario or Lucina.)

Wishful Thinking:
Ridley
(Let's make one thing clear: I hate Metroid. But Sakurai's various passive-aggressive potshots towards his fans during Smash 4's development were just flat-out cruel. So if he were to be put in SSF2, I'd welcome him with open arms.)

Shoe-In:
Mewtwo

Likely:
Lucas

Surprise:
Scrooge McDuck

Not Likely:
Klonoa

No Chance:
Wii Fit Trainer

Hell No:
Chrom

Wishful Thinking:
Banjo-Kazooie