I'll piggy back off of your scenario, of a replenished Hannibal in Italy.
So let's say Hannibal gets reinforcements that give his army a number of 50,000, which isn't as unreasonable as it seems. I distinctly remember compiling a number of between 35-50K troops Carthage sent to various places, Sardinia, Spain, amongst others, instead of to Hannibal. Hannibal, having campaigned on the ground he would have undoubtedly would have faced Scipio on, would have the local advantage. Scipio on the other hand might have been handicapped if he lost his Iberian army, which would be reasonable to assume so as to keep a Roman presence in Iberia to check any Carthaginian resurgence in the area.
Scipio's biggest advantage when he faced the Carthaginians in Africa is that he planned on his terms, and drilled his men to a new standard that the other Romans didn't meet. That is why he was able to pull of the brilliant victory at Illipa in the fashion he did. Take away his men, he probably would not have fared very well against Hannibal, indeed I am of the opinion he would have lost, Hannibal having the local knowledge of the terrain, cavalry advantage (Scipio wouldn't have Masinissa's Numidians), as well as troops on par with Romans in the area of arms and armor, depending on how long after Hannibal received his reinforcements and how soon Scipio attacked. The real debate in this case would be how Scipio would deal with a defeat. He wouldn't be a clumsy or rash commander as the other Romans Hannibal had faced, so the defeat wouldn't be devastating, but if Scipio decided to give battle to Hannibal, he would have a good idea in his mind that the odds were equal, or in his favor, and thus it would be major. The fact he broke his string of victories might have shaken any support he had at the Senate, and possibly even his own troops. The greatest of Roman commanders himself loses to Hannibal? How can we face this guy?? Scipio would be hard pressed to get another army to face him with, and would most likely revert to the Fabian strategy of denying him more victories and area. Thus the great Scipio would go down in history as the Roman who took Iberia, and that's it.
I don't believe this would change the outcome of the war. I do believe Rome would emerge victorious, though at a much greater cost. They dedicated too much to the war to have it merely be a status quo result. I do think Carthage would have been better off though. The Numidians wouldn't get the Roman support they needed to infringe upon Carthaginian territory, and Carthage would've been forced to increase its hold on Africa even more after the war, meaning I believe Hanno would get his way in taking more of Africa. The Barcids and Hannoids might have allied themselves politically, and I can't see any reason why this would be bad for Carthage aside from perhaps making Rome nervous as Carthage would extremely prosperous (Hanno was in favor of agriculture and mercantilism based off of it), knowledgeably in warfare (Hannibal would no doubt have influenced any army that remained, arming its soldiers in the Roman fashion if it armed its men) and not crippled from a pesky Roman backed Numidian threat.
All of that could probably be formatted and stated better, but meh, I'll leave it as is.
I am the Carthaginian who became an angel, and surrendered his wings for a life on the sea of battle.
My magic screen is constantly bombarded with nubile young things eager to please these old eyes. This truly is a wonderful period in which to exist! - Terikel the Deflowerer