No he'll never learn the amount of techniques that Hiruzen learned, and could POSSIBLY learn.
5 Nature's means = Unlimited techniques and creations
At best Konohamaru will have Fire and one more. He wasn't shown to be a genius at any point in this manga, while most shinobi who grew to actually break the bracket of substantial normality showcase it at a rather young age.
It said Hiruzen knew all jutsus in Konoha, knowing them and being able to use them are two different things and he could know all of the jutsus in the village back in his prime but that doesn't mean he knows of new jutsus over the years. You can learn many jutsus with 2 or 3 elements than someone with all 5 if you have the training. It takes time to learn jutsus and Naruto was the first we know train with clones with Konohamaru being his teacher. Hiruzen is dead, he isn't learning any new jutsus where as Konohamaru is still young and can.
You can train to learn all 5 elements, Kakashi, Tobirama, and Hiruzen all are examples of that from the DB. In part 1 Konohamaru shown to have a high understanding of chakra. Hasn't shown to be a genius? As a 12 or so year old he was fighting one of Pein's bodies and was analyzing his abilities and fighting style using the shadow clone
You must be registered for see links
. He learned about the clones giving him knowledge and experience on his own and used it against a high jounin-kage level opponent. Hiruzen was older than that when made Hokage and even then nothing special was said about him but him hyping himself up at that time.
When Naruto said he heard about Konohamaru using Rasengan on Pein, he said Konohamaru was a faster learner than him
You must be registered for see links
. Naruto learned the Rasengan in a little over a month so a Konohamaru learned it faster and Naruto learning it so fast and at a young age was a big deal as seen by Tsunade, Orochimaru, Kabuto, Kakashi and Sasuke's reaction to seeing it. So Konohamaru shown to be a genius pre-academy and as a Genin (age 12 I believe) where as you can't say anything about Hiruzen at that age. Kakashi graduated from the academy at age 5 and became a chunin at age 6 but had 3 known elements in Shippuden when he was training Naruto at age 33 (?) But the DB said he has all elements by war time. So is Kakashi stronger than Sasuke, Itachi, A, and others on Kage level?
Konohamaru learning up to 3+ elements by the age of 22 is not a problem, Minato had like 4 elements when he died 24. Shadow clones allow him to learn jutsus faster if he trains with them and he learns faster than Naruto who learns at a pretty fast rate himself plus the amount of jutsus you have doesn't mean you can beat someone. Part 1 Kakashi who knew over 1000 jutsus couldn't beat Itachi right? Can he beat strong kage level ninjas with those ninjutsus? Not likely.
Genin Konohamaru is stronger than part 1 base Naruto and much more strategic. He beat a ninja stronger than anyone Part 1 Naruto, Sasuke, Neji, or Lee beat. If that's not enough proof of him having natural talent as Hiruzen then idk what you want since it doesn't show Konohamaru much.
