I think that doesn't mean that Naruto wouldn't learn summoning jutsu at all, perhaps signing different contract (I'm not sure if signing contract is required). All of the Legendary Sanin have different summons: Yiraya toads, Orohimaru snakes, Tsunade snails; Kakashi dogs, IIRC Sarutobi monkeys.Chapter 16: Mortal Combat
“The old pervert was showing me some new moves, and something called summoning technique,” Naruto explained. “He said I could learn it, but first I had to sign a special contract.” He shrugged. “You said I should be careful about signing any sort of contract and to talk to you before I did.”
...
Naruto shook his head. “No way am I signing that scroll now,” he declared.
Kurenai merely raised an eyebrow and awaited his explanation.
“The old pervert was showing off when he demonstrated the technique,” Naruto began. “Some of those toads are really big. I wouldn’t dare try using them when we’re on a mission – one of them might eat Shino, just to get all his bugs.”
So what summon would be good choice (or just plain funny one) for Naruto? Perhaps Mongoose as in What If: Ramen Warrior by Rorschach's Blot?
Please add your ideas, no matter how outrageous...
Edit: added Kakashi dogs