The marketing funnel was invented in 1898 by E. St Elmo Lewis as the AIDA model — Attention, Interest, Desire, Action. It dominated marketing thinking for 128 years.
It is being collapsed by AI agents that compress the funnel into a single conversation: intent expressed, options evaluated, recommendation made, action taken in one exchange.
The replacement is the 'flat funnel': brand authority feeds the agent's recommendation set; the agent compresses awareness, consideration and conversion; the brand wins by being the one the agent picks.
Implication: substantial budget reallocation away from middle-of-funnel performance media toward brand authority and the no-cast skill stack.