Monetary policy’s impact is made relevant by sticky prices. The stickier nominal salaries and fixed prices for products and services are, the greater the impact of changes in nominal money quantity.
Thing is, prices are getting less and less sticky.
Long gone is the time where the price of flights was printed in a paper catalogue updated once a year. Dynamically priced flight can include changes in fuel cost, or demand and supply pressures, every few minutes, and people got used to it. You have a ballpark idea of what a flight cost, but known that the exact price will only be known at the time of booking.
Anyone who buys tech gadgets and shops around using internet comparison engines will end up paying the producer country price, as lean distributors with little stock and tight margins pass through currency impact, and this model dominates — sticky price competitors are structurally more expensive because they need to add a buffer to both hedge currency risk, and to prevent adverse selection (people buying from them only when the exchange rate has moved favourably since the last sticky price was set). Even supermarkets now have dynamic price labels that can be updated in seconds.
What’s left of sticky prices? Wages and property are perhaps the main markets where stickiness still applies, though this too is challenged by short term rental contracts and short term employment (be it old school or gig-economy style), or variable compensation (bonus or commission based long term employment) where the net wage becomes decoupled from the notional sticky base salary. This is still a strong force, but for how long? I suspect the writing is on the wall: prices will get less and less sticky.
A possible danger for monetary policy is that backward-looking simulations use datasets from olden times, when prices were stickier than they are today, and thus unless a gradual decrease of stickiness is embedded in the model, will make increasing false predictions. More generally, monetary policy may become less and less important as nominal effects reduce, as changes to nominal quantities get absorbed by reality faster. Another reason to give fiscal policy a greater role in macro-economic management.