Let's say that Arenanet finally sticks to their original plans and has no progression anymore. What happens?
Gear gets cheaper.
The question here is: Why is this a problem? Why should that gear always retain the value or even grow in value? This argument you make isn't logical and doesn't follow - if gear has less value, then other things grow in value instead. Like it always happens in games without gear progression.
Additional tiers aren't inevitable - they're just the laziest way to appease the lowest common denominator. If they actually do it, it'd show they really didn't have much in the idea department.
Personally, I'd prefer progression in form of being able to discover more by the world actually changing large scale frequently. That, by the way, fuels progression-less games.
"lowest common denominator."
The only part that's unfortunately wrong. Whether its people that like it, people that don't give a crap or some combination of the two, they vastly outnumber the people who quit because they hated power creep.
Money speaks louder than words unfortunately.