As time goes on, I become more convinced that they should split the two apart. The "I'm a moon druid who wildshapes into something other than a beast" sorcerer might be better as a half caster, since there are some big gaps in a lot of types (also annoying if your celestial sorcerer never gets wings). Mike Mearls has been talking about the warden lately, and if that was its own class instead of being a barbarian or druid subclass, it could be a good base (if you expanded it past just being "nature stuff").
The problem with the nonbackground sorcerer is that 5e classes needs subclasses (otherwise I guess it could be the charm school wizard [that is pun, not a reference to enchantment] whose gig is "uses charisma instead of intelligence"), and we are left with few options: subclasses based on damage type (seems pretty similar to the dragon sorcerer), some kind of special casting mechanism (which would be? the closest we have to that is the wild magic sorcerer), or some kind of way to gather up magical energy (the party can only adventure in high magic areas?). None of these seem like really good options (that charm school wizard is starting to look better all the time....). I suspect that is one of the reasons we are where we are now (of course if the playtest had a second sorcerer option whose daddy was a big ball of magical energy [pre 4e eladrin perhaps?], things might be different).