[quote name='RelentlessRolento']
how the

would tekken characters be balanced against SF characters?[/QUOTE]
I actually think this would be pretty cool so hear me out.
Namco makes a Tekken / Soul Calibur styled game (3D movement, 4 attack buttons) with an assortment of Capcom characters. The projectile characters, such as Ryu, could still be in it, but the Hadoken would be an unblockable and take awhile to come out. Other characters, such as Balrog, Strider Hiryu, Hayato etc... could just have different moves as their unblockables. I would prefer the gameplay to be similar to Soul Calibur 2 but who's asking. Namco can use their roster from Tekken, Soul Calibur and other franchises.
Capcom makes a game that is a sort of mish-mash of Street Fighter IV and MvC3 (think CvS2 -on crack- in 3D). They give some of the Tekken characters, such as the Mishimas, projectiles (lightning styled projectile for Kazuya / Jin, a reppuken style projectile for Heihachi etc...) Some Soul Calibur characters could also have projectiles when it is logical (Taki shurikens, Cervantes can shoot his gun etc...) and the game feels like a faster-paced SFIV with less strict timing for the combos.
Yes it would be weird and take some getting used to. But I really think it could work (particularly the Capcom one).
... or Namco could just make a weapons based fighter with a bunch of obscure Capcom characters from Knights of the Round, Magic Sword, King of the Dragons, Black Tiger etc...