The identity of the sorcerer is its blood line (or origin). Its bloodline give him an access to raw, spontaneous and unbound magic. The various archetype give an ok feeling of the bloodline, but the feeling of raw, unbound, unique magic has been lost. The 5ed spell slot system make every caster a kind of 3.5 sorcerer, so the unique feeling is lost. Meta magic remains the only mechanic that give a good feeling of unbound magic, but it is poorly related to blood line.
Sorcerer Spell list give poor choices to reach the diverse bloodline. Its restrained choices dont help much to have the feeling of unbound magic. The Spell slot give the feeling of doing magic like any other caster.
So easy upgrade:
Outbound magic: Half of your spells and cantrips may be pick from Druid, Cleric or Wizard spell list. Wont break anything.
Outbound casting: You may use the spell point variant describe in the DMG. Will give a unique casting mechanic to Sorcerer.
Sorcerer Spell list give poor choices to reach the diverse bloodline. Its restrained choices dont help much to have the feeling of unbound magic. The Spell slot give the feeling of doing magic like any other caster.
So easy upgrade:
Outbound magic: Half of your spells and cantrips may be pick from Druid, Cleric or Wizard spell list. Wont break anything.
Outbound casting: You may use the spell point variant describe in the DMG. Will give a unique casting mechanic to Sorcerer.