For simple sites like blogs, simple low volume ecommerce, etc.
But for more "serious" eCommerce, SAAS based applications and sites that are concerned with marketing on email, social and web then then optimizing what you show then and finally generating leads for salespeople to call or actual sales...
Cookies or local storage, or some way of tracking the customer across all the channels and their actions are essential.
If one can avoid using Google Analytics, then that's a good thing also.
But let's get real -- the idea of a cookie-less future is not gonna happen because people actually do business in the web.