Dear Paul et al,
While the musket did reduce the importance of the bow on the battle field it never killed it completely. The muskets took quite a bit of time to reload and fire, and weren't much use in the rain. An archer could fire a large number of arrows in the time it took to reload.
Although, if memory serves (and it seldom does), while the Takeda clan did have a number of men with muskets it was Oda Nobunaga's superior firepower that sealed the deal for Katsuyori.
Best regards,