While it’s wonderful that Hawaii Five-0’s showrunner seems to have more storylines he wants to explore in future seasons, CBS hasn’t renewed the show for Season 11 yet. Though it’s not unheard of for a network to hand out multiple season renewals in advance – like NBC did when it renewed New Amsterdam for three more seasons – getting picked up for several more seasons is obviously not a guarantee.
That said, I think it’s probably best to introduce Junior’s “long story” sooner rather than later, just in case.