Well I wouldn't mind if it was more MOBA-like in the multiplayer aspect. Giving the player a little less control over the units. Or maybe even have that be optional. Like there could be a "simple" mode for multiplayer in BL2 where the units just operate of their own volition and the player CAN order them about or double team with them, but doesn't control production of units or HAVE to tell them where to go because they'll always be advancing towards the enemy stage and destroying enemy merch booths/enemies on the way.
However, that could just be COMPLETELY optional as a game mode in multiplayer and the normal multiplayer would just have the regular stage battles as they are with whatever refinements DF would make.
Here's what I would LIKE to see in a sequel most of all though:
-More customization of Player Character/A completely customized Player Character that isn't established already
-Different acquirable vehicles to summon.
-Solos that are ALWAYS useful in combat that way you don't have relic raiser taking up space and therefore have to gimp every other character in mulitplayer because one of them has a useless-in-combat solo.
-RPG elements? Just the ability to level up some stats without it relying completely on collectibles because only raising our health when we found bound serpents got a little annoying and it kind of breaks the game if the player can already locate all the bound serpents ahead of time. If it's based on levelling up or perks that can be earned by spending Fire Tributes then it feels more like progression.
-Cosmetic stuff for your army would be nice.
-Upgrades for units/general stage battle related stuff outside of stage battles in Singleplayer/multiplayer. Like by earning fire tributes inside the singleplayer and multiplayer the player could buy perks like faster build times or ability to make mistakes in solos and still have them work. This would break mulitplayer unless a tiered system was in place to make sure a newbie wouldn't face up against a max level guy who can build top-tier units in the first few seconds. But in singleplayer it would really help the sense of progression if you could buy perks for your army. Oh, and I'd totally work for perks that increase the speed at which I can do solos so I don't die in the midst of Bring It On Home or Facemelter when it really counts.
-More songs Can't have too much metal right?
-DEATH TO ALL ESCORT MISSIONS! Just scrap them all, please.
-More varied sidequests. Because hearing "Hey who we ambushin'?" "Bad guys! Wanna help?" a hundred times gets old. Stuff like Wingman was a great break from the racing/ambushing sidemissions. Have us use our abilities in unique ways to overcome challenges.
-I think jumping would also be nice.
-If it's possible, more wildlife. The amount of variation was ASTOUNDING in Brutal Legend, much more creativity that I would expect from a developer, so even if there was the same wildlife, I would be happy.
-NEW GAME+/MULTIPLE SAVES! This way we don't have to overwrite our files just because we want to experience the Brutal Legend all over again. Or just have a mission replay feature.
-Bringing in more metal icons would be awesome. Can we get some representation for Death Metal/Thrash Metal/Power Metal? Bring in guys like Mark Greenway, Jessie Sanchez, Martie Friedman, Brendan Small, Tony Kakko, James LaBrie.
-Custom soundtracks for PC version, so we can put our own songs into the mouth of metal, because sometimes a band we REALLY love wasn't included. Like Blind Guardian, Bonded By Blood, Kataklysm, Arch Enemy, Pantera, Nightwish, etc.
EDIT: A minimap would be nice during singleplayer to keep track of where the hell I am without having to open the map every five seconds I played for over 20 hours and still needed it because it was easy to fall off cliffs with the way the driving physics were.
But at the end of the day, if there IS a Brutal Legend 2, I will buy it. With or without any major changes.