I wouldn't mind seeing something that would hammer home the concept that the mage is a pet class/summoner more than anything else.
The summon monster spells may have a use for the levels before you get new summoned spells, but they aren't that vital to the class to require legitimate replacement with a completely new spell chain, in my opinion. Sure, it would be nice, but since mages are obviously not broken as-is, replacing these spells with something that doesn't have a direct impact on a mage's survivability or utility wouldn't do any harm.
A few spells that exist for fun or utility would be nice, some ideas I've had include (and I make no claims for balance or quality, these are just things I've thought of the past day or so, some of them would probably be a bad idea to implement):
Pet HoT Spells
Pet Buff Spells for AC, HP, and/or Resists
Pet Grow Spell (Huge Companion to counter Tiny Companion, it would be fun/funny or just something to keep you from being entirely bored when you can't get a group)
Voice Graft equivalent
Mass Bandage Summons (100/cast), Mass Arrow and Throwing Dagger Summons (100/cast, again)
"Bag of Provisions" Summon that creates a bag with food, drink, bandages, a coldstone, arrows and throwing daggers
More types of summoned weapons (2h slashing, 2h piercing, hand to hand)
Summoned alcohol, party items (spin the bottle!), etc.
Pet sacrifice spells, cast a spell that causes your pet to die in exchange for some nice effect (probably need a long cooldown on pet resummon to keep from being OH EXPLOITABLE).
Pet frenzy spells that give a powerful short-term boost to pet combat prowess while draining hit points and causing them to die at the end of the duration.
A summoned expendible invisbility item similar to levitation rings or mod rods.
I could probably think of a few more ideas given some time.