It's a commonly held belief that younger people do more shopping online than in brick-and-mortar stores. Deloitte's 2017 Holiday Retail Survey confirms that trend, noting that millennials do most of their holiday shopping online.
The survey also found that the younger Generation Z (10- to 17-year-olds) spent 61% of their holiday budgets online and just 35% in stores. Generation X shoppers spent 52% of their budgets online, baby boomers spent 48%, and seniors spent just 33%.

Data source: Deloitte. Chart by author.
However, Deloitte's holiday survey might not reflect year-round spending habits. Back in September, research firm First Insight claimed that 71% of millennials visit multiple brick-and-mortar stores to find the best deals, compared to just 57% of baby boomers.
Back in June, CouponFollow found that 76% of millennials "browse the internet before buying anything." Of those, 67% buy the product from a brick-and-mortar store, while just 33% make the purchase online.
These reports indicate that while online sales are still gaining momentum with younger shoppers, it's probably premature to claim that Amazon will render most brick-and-mortar retailers obsolete. Meanwhile, omnichannel solutions like in-store pickup will likely help innovative retailers keep pace with online marketplaces.