Sure, Kakashi is present in the Boruto manga. His role might not be as prominent as in the Naruto series, but he still has significant moments and interactions.
Boruto's strength in the manga is considerable. He's developed new jutsus and strategies, and has overcome many tough challenges. His potential keeps increasing as the story progresses.
Kakashi is very much alive in the Boruto manga. The manga doesn't include his death. Maybe you got some misinformation or confused it with another character's fate. But for sure, Kakashi is around.
His training and newfound knowledge play a role too. He could discover ancient ninja scrolls or be trained by a hermit. This might lead to him learning new jutsus or improving his existing ones. For example, he could master a more powerful form of the Chidori that can cut through almost anything. Also, his physical strength and speed could be increased through special training regimens.
Naruto would be devastated. He might blame himself for not being able to protect his son. Sasuke would be angry and would likely go on a hunt for the perpetrator. His friends like Sarada and Mitsuki would be heartbroken. Sarada might vow to become stronger to prevent such a tragedy from happening again.
Boruto's reaction would be complex. He'd be heartbroken, for sure. He might start to question his own worth and purpose. But over time, he'd realize that he has to carry on Naruto's legacy. He'd become more serious and focused. He'd also become more empathetic towards others, understanding the weight of sacrifice. He might even start to study Naruto's techniques and leadership style more closely, trying to emulate the things that made Naruto such a great Hokage and hero.
Well, as of now, it's hard to say exactly how long the Boruto manga will be. It all depends on the author's plans and the story's development. But it's been building up a significant amount of content over time.