I wouldn't mind if they made a sequel (very up in the air, I know) but changed up the mechanics a bit. Either with a health system or being able to use meter in different ways. Something to curb the very hit-confirmy nature of the gameplay right now.
That's what it has come down to is hit confirms, because at the end of the day it's about supers, the only way to kill your opponent. The problem is if the game is about that and getting your opponent in a position where you can pull off your hit confirm (or get to a higher lvl which rewards you with an easier confirm or easier kill), but only a handful of characters are great at this, and again those top 3 are just so amazing at it... I would stretch it to 4 or 5 with the order being- 1. Kat 2. Drake 3. Raiden 4. Kratos 5. Sly
This is followed by a couple others who have ridiculously easy confirms and multiple ways to come at you such as- Fat Princess, Evil Cole, Good Cole.
Then of course there is the mid tier- Parappa, Toro, etc.
and finally
Big Daddy, and sir Daniel.
Again there is no such thing as a perfectly balanced fighting game, but damn the top tier is SO much higher than the 2nd tier, which is SO much higher than the 3rd tier, which is about normally higher from the 4th.
edit- Went on a tangent there.
If a second one happens Sony must first secure some big name characters. Sony marketed on 1 part nostalgia (polygon man, sweeth tooth and parappa) 1 part big name appeal (Kratos, Drake, Big Daddy) and then a bunch of randoms basically. There's obviously more to it than that, but the main characters they seemed to be pushing were Parappa- Solid, Kratos- great, Drake- great, Fat princess- WTF?!, and some others. They needed more of each with bigger names in each category. Here's how they could make this a success IMO.
1. Bring big names and nostalgia together- Crash Bandicoot, Spyro, Cloud, Sephiroth, etc. There need to be once big name characters in there. Parappa was a decent sized game, but never an iconic game in the gaming market. Crash was the mascot for the PS1, Cloud/Sephiroth are arguably 2 of the most popular characters from one of the biggest series ever.
2. Bigger Big names- Drake and Kratos are nice, more recently popular gaming characters, but there are not only bigger, but ones that have been around longer as well. Big Daddy had the right idea of going 3rd party, but he's not quite big enough. They got the wrong character from the metal gear series... they used the wrong Dante character model... they even got the wrong character from tekken IMO.
3. Finally playability- So from everybody I've talked to about this game they either know very few characters in the game, or have no idea how it is played. I was talking recently with a few friends and they kept asking... well how do you play defense? What's the point of attacking a specific character? Well the fact is when you dig in it all makes sense, but at the same time, it causes all the problems I mentioned above in terms of the unbalance with supers and hit confirms. EIiher they need to add in a factor of how quickly characters lose their ap, or for that matter ways to effectively decrease AP, better than just throws or the occasional item. Again this is getting too deep.... scrap it all together, incorporate ring outs and a health system, and you have a damn good game on your hands.